Simms G4 Pro Powerlock FELT Overnight they are protected by four durable film construction is they are protected by four special fingers which keep your bullets from hitting the bottom of the box and causing tip damage (which can change flight characteristics) The Foam is approximately 7mm thick at the heel and under the ball of the foot before tapering to 5mm at the toes Simms G4 Pro Powerlock FELT Boot is the most advanced wading boot on the water G4 PRO Powerlock Boot – Felt offers supreme durability and superior grip thanks to state of the art materials working in lockstep with the new Powerlock cleat system for on the fly traction customization