I don't use collars, as bichons are prone to collapsed tracheas. So I use harnesses. The girls wear red ones, the boys wear blue ones. From Pet Edge, the step in aka two step harness. I also find this type at Target. Mostly I just have the 4 harnesses, once in a while if Target had a sale I'll have a few extras. I have a bad habit of stepping on (and crushing) the plastic buckles.

That said, I have a huge assortment of collars! I haven't ever bought a collar, and yet some how, I have over a dozen! Fancy and plain, buckles and clips. (None are rolled, which are mainly for long coats. In a proper cut, a bichon has a long coat. Go figure!) I can't even tell you where most of these collars came from, they just seem to multiply in my closet!