Hexentrics, originally designed by Yvon Chouinard, are one of the most successful designs of large nuts (chocks) ever produced.
The clever uneven sides mean that there are three sizes of placement each nut will fit, and they can also be cammed in horizontal breaks.
Although large nuts like these have been superseded to a certain extent by camming devices, there are nevertheless many instances where camming devices are not as secure as a well placed "Hex", and every climber should know how to use them.
Black Diamond Hexes are nowadays only available on "floppy" wire (for better camming placements). They are colour coded for ease of recognition.
They are also available as a part-set of sizes 4-10 with a free BD Hotwire wiregate krab.