I've been aware of this pin for 25 years but never saw one for sale. It dates from 1983-86. I still need the Krukow (also unseen for 25 years) to complete the set. Speaking of 25 years, that's how long it's been since any licensed Giants photo pins have been produced (1993). The last set I know of was Bonds, Clark, Thompson and Williams. Any pins you might see of Bumgarner, Posey, Lincecum, etc. are all bootlegs.
Side note on Hammaker: not exactly an exalted Giant. He is the ONLY pitcher to ever give up a grand slam in an All Star game and lost game 7 of the 1987 NLCS when Roger Craig probably should have started Krukow. To add to the ignominy of the 1983 AS game, fat Tommy Lasorda waddled out to the mound to pull Atlee.