Billet aluminum firewall rings to run four hoses (two heaters, two a/c) through the firewall. 

The a/c rings have to be slid on the hose prior to crimping the line. These firewall rings are a great way to avoid metal cutting into the hoses, while keeping a clean look.

Firewall ring diameter:
#6 hose 15/16″ mounting hole diameter/ 1-3/16″ outer diameter
#10 & heater hose 1-3/16″ mounting hole diameter/ 1-3/8″ outer diameter