Plastic blast gates - 3" (75mm). Allows you to shut off a section of your collection system for tools you are not using. Doing this helps to curb air loss throughout your dust collection setup.
For those wishing to know the internal and external dimensions for connecting to existing machines or other setups. 72mm to 76mm taper making it ideal for 3" hose.
Remember to always have at least one line open at all times. Also position the blast gate so it slides sideways, rather than up and down, so the vibrations do not close it during use.