Split Aluminium Collar R800-CL-8M-2187Split Aluminium Collar8 Magnet Collar Suit 2. 187" Shaft R800 CL 8M 2187 00 CL 8M 2187 These aluminum split collars provide a mounting platform for the magnets that are used to trigger the sensor when monitoring the revolutions of a shaft. They are typically used on rear end yokes or couplers to provide driveshaft RPM. Each collar is approximately . 375 wide and houses two magnets which are located 180 apart. Custom size and dual magnet collars are