Article reference KA-01157
The only difference is the shape of the baffle (front cover) included in the box. The last letter identifies the shape and below is an easy way to remember them:
S = Square
R = Round
SR = Both square and round
Top tip to help you choose - Square fans usually go on the wall to blend in with tiles. Round fans usually go in the ceiling to reduce any possible alignment issues. It is all down to personal preference though so the C4TSR gives you both options and you can decide yourself or even change it up from time to time!
Applicable Models:
C4S C4R C4SR
C4TS C4TR C4TSR
C4HTS C4HTR C4HTSR
C4PS C4PR C4PSR