Square D B7.70 Thermal Unit Brand: Square D. Part Number: B7.70. Square D Thermal Unit, Melting Alloy, 600 VAC, 4.46 to 6.27 A Full Load, Class 77/Standard Trip, 4.9 in L x 3.5 in W x 0.8 in H Size, Plug-In Mounting, 40 deg C. Additional Description: SQD -B7.70 THERMAL UNIT. Catalog Description: Thermal Unit, Type S, Type B, melting alloy, Class 20..