it is really simple. the valve is a plastic frame with rubber flaps on the inside of the frame. there is foam surrounding it to act like a filter in case it is needed. when the passageway is blocked(ie submersion) the flaps suck in and let air bypass the bottom of the tube. you have install the bypass valve in a certain aread of the intake tube for it to be effective, you will probably lose some power, and you probably will have to cut your intake tube. AEM actually supplies you with a paper template so you can cut the intake tube to the proper dimensions. The valve aslo comes with a CARB sticker to put on your intake. I helped a friend install his valve onto his AEM intake. We experienced a slight loss of power, but that was on a Civic EX

 

in P.R it rains a LOT and i have the RRM CAI and i've never experienced this problem.