The Rock Rings are thicker than the factory outer wiper seal rings, and require longer bolts. Rather than running a hex head bolt, Low Range prefers button head socket head bolts that do not protrude from the ring.
If you were to go down to the hardware store you would find the following: 1. They probably will only have standard head allen, and maybe not even metric sized bolts. 2. They would cost an arm and a leg. Low Range special order these in large quantities so that you don't have to search a million places for them.