Air Gap InternationalET116-001 Drain Line Adapter (DLA) With 1/4-inch Quick Connect Fitting for a Water Filter and 7/8-inch Fitting for a Dishwasher

This is a great way to not have to drill holes in your pipes when installing a RO system. Enables you to install inline with existing dishwasher drain hose. Only con way too expensive. Apparently nobody else makes this. I would say it's worth it in the long run.

Used this to connect reverse osmosis drain to disposal dishwasher drain

This was super easy to install and allowed me to run my RO system (which is housed under my kitchen sink) directly to the outlet from my dishwasher. Simple, easy, cheap. Can't complain about that!

I bought it for my reverse osmosis. I don’t have garbage disposal, so it works perfectly. Fits perfectly and no leakage.

This adapter is of high quality and holds well to the pipe, and it's also easy to connect the water filter hose. However, it might not work well for everyone due to the narrowing of the water passage. Unexpectedly for me, I understood why filter manufacturers recommend drilling a hole in the pipes instead of including this adapter in the set, because drilling doesn't reduce the pipe diameter, unlike the adapter.For me it doesn't work as expected because it narrows the water passage channel. When connected, the water entering from the other side of the dishwasher doesn't drain quickly enough and overflows through the safety valve.