Fuse panel, 4 circuit, with switches, Watertight, 3 phase feed, single phase loads, 125 Volts. Fuse capacity is up to 30 amps but the branch circuits are limited to 10 amps by the rating of the DPST switches (Type 1SR2A4) that are used to control the branch circuits. Uses Type F09 fuses. Feeder cable size 14 MCM maximum. Branch cable size rated at 4 MCM by the military specification. Connection to the branch circuits is at the switch terminals which have #5-40 screws. Ring type lugs are recommended. Brass enclosure, size 10x13x3 per MIL-E-24142/6 with fuse door for access to fuses. Symbol 649.1 per MIL-DTL-24646/11. Military PN M24646/11-003. NSN 6110-00-174-1653. Similar to Symbol 645 which has a single phase feeder bus and the Symbol 645.1 which has a single phase split feeder bus.