Air Switch, 3 terminal, latching. Used in many spa controls. Single Pole, Double Throw, SPDT. 25 Amp Contacts. This switch is also the perfect replacement for the TBS-310, and the TBS-305 spa control air switch. If you are replacing a latching air switch with only 2 terminals, just ignore the third terminal and connect to the two that are used on your old switch. Amp ratings on the old switch can be LESS that the 25 amp rating on this switch. This refers to the capacity of the swtich points only.