At DogFit we have put together a complete kit for everything you need to start Canicrossing with your dog. This is the same equipment that we use regularly ourselves and highly recommend.
The Zero DC Short is an excellent entry-level harness or for regular runners with small to medium dogs. It’s fine for large dogs, too, if they don’t pull excessively*
Set up is easy: simply place over your dog’s head, keeping the part with the metal ring facing towards the hindquarters, before popping the front panel through your dog’s front legs and fastening both sides together under the belly. Fully adjustable straps to ensure a comfortable fit.