My (female) partner and I have been exploring anal plugs for about six years. Before that, we'd had a couple of plugs that were used very infrequently, but honestly the quality of tools/toys available 10+ years ago was nothing remotely like it is today. As the quality and variety of toys increased, we tried again and found we had more fun.

We liked the idea of glass as a material for ass plugs because how easy they are to clean, how well they work with lubricants, and they are aesthetically pleasing. We'd purchased several other glass plugs over the years, but most of them had problems. A lot have too much of a taper on the external flare, making it possible to push inside, which is not desirable or fun.

The Sasha Grey Medium Black Glass Plug is a surprisingly well designed and implemented ass plug, with a good ratio of width to length and a very secure-feeling flat base.

The size is on the larger side for a 'medium', as other reviewers have noted. Most folks will need plenty of warmup or experience or insertion will hurt at max width, but it settles immediately back down to a comfortable size. It's large enough that it can either be great or too much to add to vaginal intercourse, depending on size and compatibility of the male and female parts. That is to say, the man can feel quite a bit of pressure from the head of the plug when inserted into the vagina.

Because it's glass, it works really well with any lubricant, though we normally prefer silicone based because they don't get sticky or crusty fast. For longer erotic moments, choosing the right lube can mean less annoyance and maintenance. More Eros, less janitor.

The color is great, understated, not trying to go for crazy, swirly, etc. It's kind of plain, but elegant.

This has become one of my partner's favorite plugs in the last couple months. It doesn't serve the same purpose as some of the other types of plugs and usually wants to be proceeded by something a little smaller (FunFactory Bootie, the Sasha Grey Small Black Plug, etc), but it has been a great addition to our 2012 sex lives.

This can be good for people who want to add a little submissiveness to an otherwise straight sexual encounter, to add extra sensation/fullness to a straight fucking, or for riding a while to get warmed up. We haven't used it as an extended wear plug, but the design is such that it will not slip inside, so it's possible someone could try it for longer periods or out in public.