John Guest Speedfit 3/8 x 3/8 x 1/4 Inch Angle Stop Adapter Valve, Push to Connect Plastic Plumbing Fitting, ASVPP1LF

I used this product to my undersink water filter. I particularly like the shutoff valve that will make it easier to change the filter cartridge without turning off the main supply.

This is much better than the crappy splitter valve that comes with RO systems. My RO splitter valve froze up in hard water conditions and would not shut off. This valve should fare better. The push-connect is very handy and quick to hook up a 1/4 RO system. The ability to rotate the center section is very nice to orient this connection appropriately. Update (12-26-2016): 6 months out, it was time to change the carbon filters in the RO unit, and this shutoff valve still operates just fine in hard water conditions and allows for easy maintenance.

My first valve leaked and contacted the seller. They replaced it for free with shipping included and the new valve works perfect and is a 5 min install. I would buy again.

Everything was sized as advertised, with exactly the same difficulty of installation as any other adapter. You need to allow space for the valve handle, since its bulkier than the rest of the fitting. The plastic parts dont feel cheap, and the valve was firm enough that it wont be turned accidentally, but still not difficult to turn. This is great under the sink with cleansers and things that might bump into it. If youre looking for a valve to be turned on and off a lot, this is probably not what youre looking for, but its an excellent choice for under-the-sink fittings that will only be used during maintenance or upgrades.

My previous valve was twice the size and additional fittings (adapters). This just fits into the angle stop valve under the kitchen sink and the faucet host. This valve is also much easier to turn on and off.

This was exactly what I needed.

Most R.O. systems you buy dont include something like this, they only have a straight connection to your cold water supply. This means no way to connect the line to your sink. This little baby solves that problem. It is perfect for installing a reverse osmosis unit and a lot of other stuff also. Another thing to mention is this can install right on top of your existing cold water shut-off valve so you dont have to shut the water off at the meter. You could also use this to only shut off the water to the R.O unit to service it while leaving your sink water on. This is such a must have I really dont see why it isnt included with the R.O. unit.

I rarely write review, but this one is just too good. No leak, installed it within 3 minutes even I am a rookie in water system. Now this thing sit nicely under my sink and I just connect the pipe from RO/DI when I need RO water for my aquarium.

My plumber said this piece saved the install of our water system

Im a plumber and Im impressed. Both this adapter and the similar one for ⅜ tubing make adding a water filter or icemaker line very easy and have a well made valve so you have the ability to shut off the water out the side. This can be installed in tight spaces because the metal part rotates (as in to install) and the white part rotates 360 degrees as needed. Thats also helpful becaues you can turn it to avoid tangling your ice maker/water filter lines with pull out spouts or spayers.