TweetYou don't need to worry about the plunger, it is very heat resistant. If I remember correctly around 325. I actually use them as stirring sticks when mixing heated oils and powders at temps up to 175. the casings will melt and or warp at a much lower temp. I believe around 200. which is of no concern as you would never heat a syringe or it's contents meant for injection to this level.