What does a coupler attach to a bag ?
Coupler is a word used to describe any of a number of things : A railway coupling device ; * A Janney coupler ; An electronic device such as : * An acoustic coupler for coupling electrical signals by acoustical means ; * A telecommunications device known as a directional coupler ; * An antenna coupler also referred to as an Antenna tuner * A kind of laser mirror known as an output coupler ; A connector between two moving parts to relay the motion , such as a Universal joint or an Oldham coupler .