Audio Connectors - 1/4" TRS (Tip/Ring/Sleeve - Stereo) - Chassis Mount (receptacle) - 1/4" Professional phone plugs are available in TS (Tip/Sleeve - mono) and TRS (Tip/Ring/Sleeve - Stereo) configurations, and are used universally for balanced and unbalanced audio connections between audio equipment, and instruments. CHASSIS MOUNT RECEPTACLE TRS