Review on Allstar ALL50821 Aluminum 3AN Thread by Bill Howard

I wanted to protect the equipment I just installed from contamination. It's for this purpose. I installed a new hydraulic clutch master cylinder, but didn't install a manual transmission with a hydraulic release bearing until winter. This allowed me to drive an automatic car until I had to change the transmission. In my case there was no fluid in the system, I just wanted to keep it clean until I was ready to change the transmission. In the meantime I have changed the transmission, the lines have remained clean as intended. These caps are reusable, although soft enough to be easily crushed with pliers. It was worth the money. Please note that they are not designed for use under pressure. If you need to close off a line that is in use, do not use these caps.