T bar Allen keys, T handle Allen keys or T handle hex keys are a hexagonal Allen key with a T shaped handle at one end which is perpendicular to the shaft. The T shaped handle has an ergonomic design which allows the whole handle to fit comfortably in the palm of the hand with some handles having soft rounded recesses for the fingers. This handle design creates an improved grip and allows the user to apply more torque to screws without causing excessive strain to the hands as well as reducing fatigue if using the tool for prolonged periods of time