I can take a 8in long x 1.75 wide strap on. I prefer to bring my own to a session. Unless the provider happens to have one that size, already.
For an added "kick". I like to cover the dildo with either the Kimono MicroThin Ribbed + Sensi-dots or the Rough Rider studded condoms. Which I'll bring with me. Plus a bottle of my favorite lube, Toko Silicone as well. This lube is both latex and body safe.