Square D A2.81 Thermal Unit Brand: Square D. Part Number: A2.81. Square D, A2.81, Overload Heater, Melting Alloy, 600 V AC, 2.32 to 2.92 A Full Load, Class 20/Standard Trip, 3.6 in L x 2.6 in W x 1.7 in H Size, Plug-In Mounting, 40 deg C. Additional Description: SQD -A2.81 THERMAL UNIT. Catalog Description: Thermal Unit, Type S, Type A, melting alloy, Class 20..