The boxstix dual tab II is designed and patented to suit the FCSII fin system 

Each 2 - pack contains:

2 x FCSII Boxstix plugs
Leash String
Soft Carry Case

Fins are the driving force behind every turn and maneuver you do… don’t be held back by an empty finbox "close the gap of unused side fins or fill the void of an empty centre finbox".