Evolution jig heads come in multiple lengths and weights. For example our 35mm jig heads measure 35mm long, have a hook eye for hook installation and a tow eye for tying your leader to. Thats right, no actual hook point at this stage. The packet contains 4 jig heads and 4 double hooks. the double hook feeds through the hook eye once the jig head is installed in your plastic. We have a variety of hook sizes from w12 (tiny) up to 2/0 (ultra strong) Check out our product guide for recommended jig head to plastic size compatibility. This is only a guide. You can mix n match as you see fit. You want to use a 45mm jig head in a 6" plastic ? go right ahead, the choice is yours with Evolution Jig Heads.