These receivers are required to allow the attachment Priefert's wishbone carriage (CA04-2 or CA04-2WT) to your model S01, S0191 or S04 Priefert squeeze chute. Priefert's innovative wishbone carriage system is simply the easiest one-man chute loading system on the market and makes moving your squeeze chute a snap. The CRS0164 is designed for use with the model S01 squeeze chute, the CRS01-2 is used with the model S0191 squeeze chute and the model S04 chute uses CRS04-2 receiver. Select the appropriate receiver and follow the simple instructions to mount it to your chute.