This spray can holster is a really great idea when you are marking lots of cows in busy times of the year like at calving.
Except if you need it for a hospital herd full of mastitis cases, you probably need to look at more than just a spray can holder.........
It is also very handy for your spray bottle of 70% alcohol disinfectant whilst doing a herd strip. (Because you do sterilise your gloves regularly whilst strip testing the herd, don't you?)
Holsters are available in both solid and flexible forms, fully mounted on a belt, suspended from a belt, etc
The leather models are a bit sturdier, and it is also easier to return the can to the holster with one hand compared to a deformable, flexible holster.
They can be purchased online or at cleaning services, some paint shops, etc., or at specialty leathergoods outlets.