I wear trousers in size 34-36. I started with a large BB after measuring the belt loop on the loop as they recommend. 8 inches between the hinges, a large BB is recommended. It got VERY big. I returned the money and received the medium. A little bigger. But on both sizes I only tried one strap on one side as it was advertised that one (or two if you prefer) could be used. Instead of sending this one back and getting a small one, I decided to add a second one. It worked this time. But I was hoping I could use one for work pants and the other for jeans after work. Before I bought a BB I went to Lowe's and bought an elastic velcro with a buckle like piece to see if I could make mine. It actually worked well and only on one side of my pants. But I thought I'd give BB a try to see how much better it was in terms of performance and quality. I can't say I'm overwhelmed. But it works. However, you will most likely need to use one on each side. You could probably put on a regular belt quicker than 2 of these BBs. The advantage of BB, however, is that the belt buckle does not cut into your stomach when you sit down. This front is belt-free! Plus, there's one less thing to unzip when a guy goes to the bathroom. BB basically turns your jeans, work pants, etc. into stretch pants. Lol But again, buy a size smaller than you think you need!