Parallax Power Supply&nbsp; FB9 Fuse Block The FB Series of products are stand alone 12VDC fuseblocks mounted on a metal offset base and flip top lid provides for protection for the DC circuit terminations and fuses Often an FB Series fuseblock along with a 7400 Series converter is used to replace older 3200 Series (now obsolete) converter systems Three DC Positive inputs for converter and Batteries. Galvanized metal chassis and hinged cover