My two cents is this. You need one that you step into and has straps supporting both sides of your thighs. The harness must be one that has a very sturdy and ajustable ring, in the front of it. This way you can insert any size dildo into it. I found mine at the Pleasure Chest, which is a store in the West Village in N.Y.C. (For those who don't know, there are 5 boroughs in N.Y.C. The west village is in Manhattan. That is the borough that most people on earth think is N.Y.C.) Even though I am now 37 and I use to work for Playboy, I want to tell you that I am still a complete nymph (please understand that I am not indicating that anyone else that ever worked for them is such, I just am!!) and I haven't lost my desire for sex, nor what I need to use to fuck with. I married a great guy whose has been extremely successful. I only tell you this because I want you to know that I have literally serched for the best strap-on, on earth. The one negative, if you want to call it that, is that it takes my slut hubby slave quite awhile to get his head up my ass and his tongue up my asshole, with the strap-on harness on me! However I don't think that is a negative. I want you all to know that when you buy a strap-on it has to be sturdy and well made so that it can handle giving some very serious ass fucking. Mine is all leather and cost a good amount of money but has lasted me years! I am sorry I can't show you a picture but I hope I have discribed it the best I can. My husband has just published his first story on Lit. The story describes a real life incident, with the exception of a few minor detail. So if you would like to learn more about me and my hubby just read his story. The title is "The Recipe for a Great Time". I love it but of course I am a bit bias!