73104 DIY Insulated BNC (M) Connectors Pomona Electronics 73104 Do-It-Yourself (DIY) Insulated BNC (M) Connectors offer increased electrical protection and accept RG 58, 58C, 141, and 141A coaxial cable types. The center conductors of these BNC connectors are made of nickel-plated brass, gold-plated brass, annealed copper, or tinned copper. Pomona Electronics 73104 BNC connectors feature CAT II 1000V/CAT III 600V voltage rating and 3A current rating. These connectors are available in black, red, and blue colors.