Blue Sea Systems ATO/ATC Fuse Block System, Integral Ground Bus Style. 12 circuit. • Clear insulating cover with label recess for small format Blue Sea Systems’ labels. • Cover insulates all conductive parts, satisfying ABYC/USCG requirements. • Tin-plated copper buses and fuse clips give 30-ampere rating per circuit. • Accepts ATO and ATC fast acting blade type fuses and plug-in style circuit breakers.