The Russian word for a kettlebell is girya, and a kettlebell lifter is known as a girevik. Kettlebell sport is sometimes called girevoy sport (or GS, for short). Kettlebells were originally measured in poods (1 pood = 16 kg), but are now available in a variety of shapes, sizes, and weights. Girevoy/kettlebell sport uses specialized kettlebells that are a bit different than those you find in most gyms and fitness-equipment stores--all the bells are the same size regardless of weight and are coded by colour. There are intermediate weights (e.g., 10 kg, 14 kg, etc) and also much heavier ones (I got tired of making kettlebells in Photoshop). Here are the most common ones:
What's so special about kettlebells? Lots, including the fact that you can burn 20 calories a minute! Instead of trying to explain it all here (and because I have no credentials for this sort of thing at all), here's a link to a blog called Kettlebell Science by an Ontario kinesiologist named Corey Wesley who seems to know what he's talking about. My favourite thing about kettlebells? Efficiency. You can an effective, full-body workout in record time. The GS workouts always leave me gasping for air--you tend to work at the high end of your aerobic capacity--but I can now easily run up hills that defeated me in the past. What's not to love?