This specification covers one type of small light weight portable, immersion proof , retractable cord type field telephone switchboard,
designated as Switchboard Telephone Manual SB-22()/PT, Switchboard Accessory Kit MX-2915()/PT and the following subassemblies of SB-22()/PT(see 6.4):
Telephone Circuit, Line Jack TA-222()/PT
Telephone Circuit, Trunk Jack TA-326()/PT
Telephone Circuit , Operators TA-221(),/PT