The Kat Walk C treadmill can only be used with these sensors. They are attached to the dedicated Kat Walk C shoes to track your leg movement. A pair of these sensors are included in the  package along with a pair of dedicated shoes. You can detach the sensors from one pair of shoes and attach them to another one.

If you wish to buy  for your treadmill, you would also need to attach these sensors for proper use.

Specs

Latency: Less than 20ms
Battery Life: 7 hours