Four rubber straps are provided in the box with your new Vetrax™ Sensor to ensure your sensor and sensor base-plate fit tightly and securely on your pet’s collar. The following is provided as a general guide. However, collars can vary, so please check multiple straps to find the one that works best for your situation.

The small rubber strap fits 3/8" collars:
  

The medium rubber strap fits 3/4" collars:
  

The large rubber strap fits 1" collars:
  

The x-large rubber strap fits collars between 1" and 1 1/4":