The ES-T® is a single-source, under-saddle transducer with individual elements for each string. It features an onboard preamp and the same active controls found on the full ES. Featuring a custom-voiced EQ and dynamic response, the system is powered by a 9-volt battery, with a battery life LED power indicator (which is lit when the battery is being used). The pickup also has a Phase switch for feedback control, which is located on the preamp board inside the soundhole. It was available on the 100 and 200 Series until 2016, when the Expression System 2 became the standard pickup.