Don't even think about trying to guess where to position the pocket, you have very little chance of getting even close. Take the time to put your exposure suit and your BCD on, then mark exactly where you want your pocket. The preferred location would be directly underneath and slightly above where your hand falls naturally on your thigh such that your fingers can reach completely into the bottom of the pocket. Some sidemount divers are now placing the pocket on the back of their thigh.
After marking the location, remove your exposure suit, lay it flat and prepare to attach the pocket using an adhesive. For exposure suits made of tri-laminate or vulcanized rubber you should use 620 Contact Adhesive. For 620 Contact Adhesive, use the applicator brush to evenly apply directly from the can on to the back of the pocket and also to the matching area on the suit. If your suit is neoprene, then you can use Aquaseal. For Aquaseal, using a disposable plastic knife like those found in fast food restaurants or similar instrument, evenly spread an entire 0.75 ounce tube of Aquaseal directly from the tube on to the back of the pocket.
Once the adhesive is applied, carefully place the pocket on to the exposure suit according to your markings. Put some weights, like a large stack of books, on the entire pocket. Allow it to cure for at least 24 hours, 48 is better, and resist the temptation to 'check on it'. It will be permanently attached to your exposure suit, as in you won't ever get it off again.
