Aappy, that's a Tom Thumb and so many people mistakenly call it a Western Snaffle. A snaffle, as you must have found out, has no shanks.
BTW, before you use that particular bit, you may want to read this article: http://www.todayshorse.com/Articles/...thTomThumb.htm
A better choice, and one that I've been using for many years, is a shanked bit with a Billy Allen mouth piece. I'm a huge fan of that bit because the barrel in the center prevents the nutcracker effect that the TT creates, it is better balanced, and the shanks can move back and forth without effecting the other side. Here are some examples but you may find them cheaper on ebay or other tack stores: http://www.rods.com/dg/235,123_Billy-Allen-Bits.html