The S & G Tool Aid Corp. 20-Piece Back Probe Kit, No.23500, is used to back probe harness connectors, fuel injectors and automotive sensors. The stainless steel probes come in straight, 45-degree and 90-degree profiles in 0.027" and 0.040" diameters. The probes are color-coded for easy identification and are compatible with the standard 4mm plug. Also included with the kit are 12" extension leads, color-coded the same as the back probes for use in recessed areas. All probes easily insert into automotive connectors. The kit is supplied in a durable, plastic storage case.