High Temp Masking Supply 1.312" x 1.625" (1-5/16 x 1-5/8) Silicone Rubber Plugs - Tapered Stoppers for Powder Coating, Painting, Automotive - Non-Toxic, Flexible, Reusable STP8 (5 Pack)

These are simple and work great. I use them at 400° all the time.

Got these to plug some tomato watering stakes so that water is released over time. Outside in the heat, they are working just fine. Edges are not rough and material has some give.

Very nice quality! I'll tell ya this much.. if you ever need to block off the exhaust port on an LCE Pro street Toyota 22RE cylinder head, this is the silicone plug you have been dreaming of. I'm using this particular size (the 1.3125 X 1.625 size) to plug up the exhaust port, so that I can aluminum oxide blast the exhaust runners, while keeping media from existing the other side, and this plug fits absolutely perfectly and very snug/tight.

Use these with a oxilic acid sublimater which operates at a temp of 390 f. Stands up as well as can be expected

I do a lot of different crafts and the above plugs worked great>

Was having trouble with my exhaust sitting on my frame for some reason. Put one of these in between while I figured out the problem. Didn't melt, didn't even deform or discolor. Impressive!

My wife and I use these to cork off one end of PVC tubes that we pour resin molds into. It works great for our purpose, and does not stick to the cured resin. Wonderful and will buy again.

Very Pleased