The 50R and 50RF series are 1/4" diameter switch sets designed for applications where a small diameter recessed switch set is required. This makes the set desirable in residential installations where no sign of an alarm system should be seen or where there is not room to install a larger diameter recessed switch set. The 50R-12 is a straight cylindrical set for flush or counter sunk installations. The 50RF-12 set is flanged to prevent inadvertent pulling of the switch into the wall.