The 1/4-inch connector is commonly called a phone connector because it was used for years by telephone operators to patch telephone connections together. It has a tip/ring/sleeve design, like the 3.5mm connector, but it is larger in length and diameter. The 1/4-inch connectors may have only a tip and sleeve, or a tip, ring and sleeve (TRS). A TRS connection is used for balanced audio lines, or depending upon the equipment, for stereo sound. The 1/4-inch connectors are very common on musical instruments (especially guitars), and other staging devices such as effects pedals, mixing consoles, speakers, and amplifiers.