 They are often preferred by alpine mountaineers over spring-loaded camming devices because of their lack of moving parts and overall lower weight for the same size crack.The original hexes were invented by Yvon Chouinard and Tom Frost, and called "Hexentrics".The "polycentric" hexentric was designed by Swedish/Norwegian climber Tomas Carlstrom and given to Chouinard Equipment in 1973.