HPS Performance 1/4 (6.5mm) Red High Temperature 3-ply Reinforced Silicone Coolant Cap Bypass Heater, 1-1/2 Length, 350F Max. Temp, 4mm Wall Thickness (RSCC-025-RED)

These are awesome. Wont crack and leak like regular vacuum plugs

Im using this to permanently cap off a small coolant tee. I tried to find a union to eliminate the tee, but Im using a combination of oddly-sized hoses, which made it really hard to find what I needed, so I just decided to cap the tee with this product. Its very thick and sturdy, and if HPS had done a better job of uploading product-specific pictures, it wouldve saved me a ton of time, as the picture on the Amazon listing isnt very representative of the actual product. Ill need to slice some length off, but Id definitely buy more, if I ever needed them.

This cap is definitely high quality, needed it for a coolant line that I needed to block off and it works great. Highly recommend especially with some good clamps.

Honda Civic. Rim under radiator cap is deteriorated where steam leaks out and through expansion tank. Radiator needs replacing but putting this cap where expansion tank hose connects will get me through the winter. Use the 1/4 inch size. Push hard to get it on. It will fit.

This little cap worked great for the unused EGR coolant port on my 1988 foxbody heater pipe. Its a quality silicone cap and should last for a long time. Definitely beats replacing a rubber cap every year.

Very high quality. Same material as their IC pipes. Shame it’s hidden behind the block

Works great for replacing the cheap cap that comes with the EGR fix kit

Used this on the coolant line coming out of the turbo on my L5P. Works great and better than the cap that come in the egr kit.