The night… It’s so dark and mysterious. Like these tunnels. Made of black borosilicate glass, the single flare plugs are smooth for comfortable wear and sold in pairs. Made in the U.S.A. Get your Midnight Black Glass Single Flare Tunnels in any of the following sizes: 8 gauge (3mm), 6 gauge (4mm), 4 gauge (5mm), 2 gauge (6mm), 0 gauge (8mm), 00 gauge (10mm), 1/2 inch (12mm), 9/16 inch (14mm), 5/8 inch (16mm), and 3/4 inch (19mm), 7/8" (22mm), 1 inch (25mm).