GIG100S has long been the best tuna bait. It makes natural drifting, swimming actions at retrieve. Sinking at free tention, it imitates wounded iwashi/sardines sinking with flattering. For yellow tails and skip jacks, skipping this bait is sometimes the only tactic to catch them. You retrieve the GIG100S on surface quite fast with fast twitching, and let GIG skip from the top to the next top of waves. The slim and heavy body casts long. The belly hook eye rotates to prevent hook off.
115S is for much heavier fish, up to 30-50kg tuna.