This newest generation of Fi Fastener, the GenX is made to support both version of the Fi 3 in circulation today and builds on the same technology used in our super popular MS5 Fastener. The body of the Fi Fastener 3 GenX is flexible to make getting the Fi in an out much easier while still holding the unit totally secure! We coupled this with our dual screw J-Clip design made from space age PTEG Carbon Fiber the same material we use for our all our clips. This clip design allows you to add the Fi Fastener GenX to any collar from 0.5 inches to 2 inches wides by selecting from our clip sizes of 1.25, 1.5 and 2 inches. With this blended, lower profile design the Fi Fastener GenX works great for dogs of all sizes an activity levels, including working dogs, rough players, adventurers and couch potatoes! The Fi Fastener 3 comes in a whole new wide array of colors and is backed by our no questions asked Life Time replacement warranty!