I've been training my ass to receive a fist. My wife's already gotten all five fingers in, but she still can't get the knuckles past my sphincter. This video shows me using: 7 x 1.5 in. diameter dildo and a 10 x 2.5 in. (almost 8 in. around) one I molded out of wax. Recently, I moved up to a 10 x 2.75 in. (8.6 in. circ.) one and I'll post that a clip of that in a couple of days. My goal is to be able to take my new creation, a 10 x 3 in., without any discomfort. Then move up to fisting from there.