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Description
4"x40" | 1950 GPD | 99.6% Salt Rejection | Seawater RO Membrane | Applied MembranesAMI 4x40 Seawater Desalination Reverse Osmosis Membranes For Watermakers and Land and Sea Based Seawater Desalinators Highest Salt Rejection Seawater RO Watermaker Membranes AMI high rejection and high productivity seawater reverse osmosis membranes are specially designed for marine applications. AMI SWRO membranes are ideal for seawater desalination in shipboard applications, watermakers, land based desalinators and sea based desalinators. AMI
AMI 4x40 Seawater Desalination Reverse Osmosis Membranes
For Watermakers and Land-and-Sea Based Seawater Desalinators
Highest Salt Rejection Seawater RO Watermaker MembranesAMI high rejection and high productivity seawater reverse osmosis membranes are specially designed for marine applications. AMI SWRO membranes are ideal for seawater desalination in shipboard applications, watermakers, land-based desalinators and sea-based desalinators. AMI Membranes are 100% Quality and Performance Tested in their ISO 9001:2015 Certified Facilities. Looking for a replacement seawater desalination membrane element for your watermaker filter system? View our Watermaker Replacement Membrane Chart.
Benefits of AMI Seawater Desalination RO Membranes:
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M-S4040A Specifications
Permeate flow and salt rejection based on 32,000 ppm NaCl feed stream, pressure and recovery listed above. Element Permeate flow may vary +/- 20% M-S4040A Operating Limits
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Related Products for use with M-S4040A Seawater Elements
| 40E100-1 | 4x40 Fiberglass Membrane Housing for Seawater RO Membranes (Water Maker Pressure Vessel) |
| C-C2510-A11 | Membrane Cleaning Cartridge with Acid Cleaner to Remove Scale Buildup and Prolong Membrane Life |
| C-C2510-A22 | Membrane Cleaning Cartridge with Alkaline Cleaner to Remove Organics and Prolong Membrane Life |
| C-C2510-A88 | Membrane Preservative Cartridge for Preserving the System and Membrane During Extended Periods of Non-Operation. |
| 655139-03 | Oil Absorbing Filter Cartridge - Oil-Water Separator Replacement Cartridge, 20" Big Blue Pentair Pentek Filter |
| H-F10100CF | Plankton Filter - 10" Standard 100 Micron Spun Polypropylene Replacement Filter Cartridge |
Common Applications for AMI Seawater Watermaker Elements:
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Physical Dimensions of AMI M-S4040A SWRO Marine Element
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Replacement Compatibility for AMI 4 x 40 SWRO Membranes
AMI 4040 membrane elements are may be used as direct replacements for most industry-standard 4" x 40" seawater Membrane elements, including: DOW FilmTec SW30-4040, Katadyn Spectra FT-MB-SW4x40 , and most other Industry-Standard 4x40 Size Seawater RO Elements - for use in any system using these membrane elements. Some common systems using these elements are:
- Spectra Farallon 1800c
- Spectra Farallon 2800c
- Spectra LandBased 1800 (Spectra LB 1800)
- Spectra LandBased 4000 (Spectra LB 4000)
- Katadyn Farallon 1800c
- Katadyn Farallon 2800c
- Katadyn LandBased 1800 (Katadyn LB 1800)
- Katadyn LandBased 4000 (Katadyn LB 4000)
- FL-1800c-110-12, FL-1800c-110-24, FL-1800c-220-12, FL-1800c-220-24, FL-1800c-24
- FL-2800c-220-12, FL-2800c-220-24
- LB-1800M, LB 1800 M, LB 1800 F, LB-1800F
- LB 4000 M, LB-4000M, LB 4000 F, LB-4000F
If you do not see your system listed or wish to learn more about compatibility, please contact us. Our certified water treatment experts will be happy to discuss your application. To ensure prompt and accurate information, please include as much information about your system as possible, such as: model, manufacturer, model of membranes being replaced, any available. product manuals or literature associated with your system, and photographs of your system or membranes.
Shipping Notes
- Free Standard Shipping on $100+ Orders to the USA.
- Except Preorder products are shipped in 48 hours.
- Delivery to the USA:
- Standard Shipping : 3-10 business days
- If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
- We offer a 30-day return/exchange service after receiving.
- Final sale items are not eligible for returns or exchanges.
- To process your return/exchange, please contact us at [email protected]
- Please click here for more details>>> Return & Exchange Policy
4.7 ★★★★★
Based on 13 reviews
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Product Reviews
★★★★★ 5
All-around thumbs up!
Size: 934W-Z, Color: Black
So far, so awesome. Easy to assemble, comfortable, arrived quickly and is exactly what I was looking for. I have a tall work bench in my new studio so I needed a chair that we could allow me to sit higher than a regular office chair and allow me to get off my feet after standing on the concrete floor. Plus its a nice looking chair that I am sure will last a long time. I love the flip-up arms and the lumbar support. This is just right!
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Reviewed in the United States on May 8, 2026
★★★★★ 5
Perfect Balance of Comfort, Support, and Style!
Size: 934-Z, Color: Black, Size: 934-Z, Color: Black
I’ve been using this chair for a few weeks now, and I’m genuinely impressed with how much of a difference it’s made in my workspace. The mesh back is one of my favorite features—it offers excellent breathability and prevents that sticky, overheated feeling you sometimes get with solid-back chairs, even after sitting for hours. The seat cushion is firm enough to give proper support but still has enough give to keep me comfortable through long workdays. It feels like the perfect middle ground between soft and supportive.
The adjustable foot ring has been a complete game changer for me. I use a taller desk setup, and having somewhere to rest my feet makes a huge difference in posture and overall comfort. Whether I’m sitting upright for focused work or leaning back to read, it’s always at the right height.
The flip-up armrests are another smart design choice. When I’m typing, I like to have them down for support, but when I’m done, I can flip them up and push the chair neatly under my desk—saving space and keeping things tidy. The casters roll smoothly on both hardwood and rugs, so I can move around easily without scraping the floor or getting stuck. The overall build quality feels solid and sturdy, with no wobbles or creaks.
Assembly was surprisingly quick—everything was clearly labeled, the parts felt durable, and it only took me about 20 minutes from opening the box to sitting in the chair. The sleek, modern look is another big plus—it blends in perfectly with my home office décor without feeling bulky or taking up too much visual space.
If you’re looking for a chair that combines comfort, ergonomic support, durability, and style, I can’t recommend this one enough. It’s equally great for work, studying, or just relaxing at your desk, and it’s definitely been worth every penny.
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Reviewed in the United States on August 12, 2025
★★★★★ 3
OK for the price, but overall comfort is avergae
Size: 934-Z, Color: Mustard
Easy to put together, color (mustard) accurate to images, and while I understand this is not a high-end chair, I feel like it still needs to be rated for its quality.
Pros: the seat cushions are fairly comfortable and it rolls well. Adjustable footrest is easy enough and mostly sturdy.
Cons: For a tall office chair, it doesn't go up high enough. I actually had to lower my standing desk to sit at it, which then isn't where I want it when I'm standing now. It's also a bit wobbly. The seat area's attachment to the post isn't as solid as it should be for a tall chair, so while sitting, it does tend to lean/slope forward and wobble side to side. The lumbar support is not adjustable, so I'm not even really sure what it does. And the armrests are not very comfortable to use. Since they are hard plastic, they are just a bit too rigid to rely on for any comfort. They are basically there to hold on to when you're getting out of the chair.
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Reviewed in the United States on May 29, 2026
★★★★★ 4
Good Value for a Tall Chair
Size: 934W-Z, Color: White
I have received this chair just today and would like to give my first impressions of it.
Height is super adjustable as well as the foot rest. My desk is very tall (~34 inches vs standard ~29 inches) and does not suit a standard height chair. This chair's height is enough to sit comfortably at mybut also still having adjustment to be even higher.
Lumbar support is a manual adjustment that can be adjusted by sliding the lumbar piece up or down and it seems it can be tiled as well.
No reclining feature or slight backrest tilt adjustment. I'm used to my chairs reclining so it feels a little awkward siting in a flat base and straight backrest. I feel like I'm sitting too forward or leaning forward slightly but is probably something I can get use to.
Easy to put together and feels very sturdy. Plastic parts of chair are made from a really sturdy plastic, like playhouse plastic materials. Wheels roll around carpet easily. Mesh seems to be a strong material, though the mesh feels kind itchy on bare skin.
Overall, I think this is a good chair to get if you're needing a tall chair for a good value and can sacrifice no backrest tilt.
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Reviewed in the United States on December 3, 2025
★★★★★ 5
Excellent value for money!
Size: 934W-Z, Color: Black, Size: 934W-Z, Color: Black
I absolutely love this office chair! I needed a chair that could support my standing desk without sacrificing comfort, and this one completely exceeded my expectations. It's incredibly sturdy and durable, well-made, and the height adjustment is super convenient, making it easy to find the perfect fit. Even during long hours of work, the seat is comfortable, and the ergonomic design effectively reduces pressure on my back and legs. I love its clean, modern look—it fits my home office perfectly. Assembly was quick and easy, and for this price, the quality is absolutely fantastic!
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Reviewed in the United States on February 24, 2026