Phonak Receiver 4.0, Replacement Receiver for Phonak Audeo Marvel M RIC Hearing Aids (2S Receiver 4.0, Right) The receivers come in three "levels" S, M and P. These are the "S" level. You can find out which level you use by looking at your current receiver. It is printed on the red or blue area of the receiver. Red is for the right side and blue is for the left side.