http://www.obsessionarchery.com/sts-shock-terminator-suppressor-p-698.html

The STS is a string supressor that mounts on your stabilizer hole and wraps around toward the string. I couldn't find the manufacturer's website because well...I'm not sure who that is...but the above link will explain it anyway.

The theory with the STS and arm slap goes as follows.....The STS stops the string at the bows brace height, not farther. People get the arm slap from the string going BEYOND brace height. We've not seen this actually work to stop arm slap at the shop, though I don't discredit it's validity.

The open stance, grip, and proper draw length are the 3 most reliable cures, IMHO. The STS is, however, GREAT at making a bow quieter.