Eh.... if you're looking to fit just a couple squash rackets, balls, and maybe some goggles, a standard backpack works fine, unless your racket's really expensive and you don't want the handle exposed at all. There are backpacks made specifically for racquetball and squash on the market - you can take a look around on eBay or your locker bike shop, or even your local squash shop if you have one or more likely your local sports store.