The WK 1510 is a WK 1500 U with a reed switch. The reed switch can be used as an alarm output or for 'Automatic Tunnel Mode' using the CM 5000D. The reed switch is a good safety feature. When the reed switch is wired to the normally closed circuit on your alarm system, anytime the winch opens it sets the alarm off! The WK 1510 is packed standard with the CM 5000D. We feel the WK 1510 is the best choice for your winch kit. We want to provide as much safety as possible. When using the WK 1510 with the CM 5000D, the winches will all fall at the same time.