Square D A6.20 Thermal Unit Brand: Square D. Part Number: A6.20. Square D Thermal Unit, Melting Alloy, 600 V AC, 4.21 to 5.61 A Full Load, Class 20/Standard Trip, 2.6 in L x 1.7 in W x 3.5 in H, Plug-In Mount, 40 deg C. Additional Description: SQD -A6.20 THERMAL UNIT. Catalog Description: Thermal Unit, Type S, Type A, melting alloy, Class 20..