These are double ended silicone jumpers intended to plug into an LVC/HVC/Parallel boards to give you access for balancing. A “jumper” has the same connector on both ends where as an “extension” has opposite sex connectors on either end. These are specially made for me and I dont think you will find them anywhere else.
4S JST-XH-5 (Hard Packs)
These are available in 6″ length and 12″ length.
(If you are looking for additional “daisy chain” jumpers you should select 5S)
EDIT: As of June 09 I am including a set of these with every kit for free. Default is 6″. So every order includes the daisy chain jumpers and balance tap jumpers.