I was looking at the daiwa seiko website at a product (see below) and it seems to me (after trying to do some japense translations using altavista), that these are little weights that you can attach to your jig.
Here is the (not so pretty) translation
Feed wooden squid expert plus sinker
As for very popular "plus sinker" when deeply aiming for the place, when the flank wind is strong when, the tide is quick, throwing doing distantly, when aiming for the pole coming out point, validity.
http://www.daiwaseik...ag/index03.html
This seems like a good idea to me. Presumably the weights are easy to attach and therefore quicker than changing jigs.
