The P243D is a fuse block designed for Form 101 semiconductor fuses with a current rating of 70–450 A, compatible with A13X and A150S fuse holders. It features a glass-filled polycarbonate or laminated phenolic insulator block with studs to accommodate bolt-in fuses, and all studs and mounting hardware are tin or zinc plated for corrosion resistance. The block has dimensions of 4.40 × 1.50 × 2.79 inches with a 1/4-20 stud size and a torque rating of 16 in-lbs. This fuse block is commonly used in semiconductor protection circuits and industrial power distribution systems where reliable overcurrent protection and compact mounting are required.