Those Deep Fire pistons were forged in the burning pits of hell to cause pain and anguish to airsofters everywhere. You might as well dip your forty bucks in BBQ sauce and eat it. That G&G piston is good, but costs about double what any piston should cost.
I don't know if your gun has a worthlessly high rate of fire or not, but for an airsoft gun that shoots less than 20 balls per freaking second, I can highly recommend Guarder, AE, and Madbull pistons. They don't cost much and last a good long time.
-BATMAN