"TUBE ""B"",20 FEET LONG. USED TO FABRICATE A MAST FOR LOW-IMPACT RESIS-TANCE STRUCTURES FOR LIGHTING SUPPORTSFOR AIRPORT APPROACH LIGHTING SYSTEMS,MODELS ALSF-2 AND MALSR.TUBE INCLUDES A TUBE SPLICE BONDED JOINT PROTRUDING 4 INCHES FROM ONE END,SPLICE JOINT 6.00 INCH OD HAS HOOP WOUND RING 7-1/4INCH OD BY 1-1/2 INCH WIDE 60 INCH FROM SPLICE JOINT END. OVER-ALL DIM. 6.000 INCH PLUS 0.005 OR MINUS 0.000 INCH ID; 6.250 INCH PLUS OR MINUS 0.031 INCH OD; 20 FT 4 IN LONG. HELIX RING JOINTS SPACED AT 42.00 INCH INTERVALS FOR FRANGIBLE JOINT. FIBER GLASS MATERIAL. PER FAA SPEC. FAA-E- 2702;ITEM 13, DRWG D-6155-1, ALSF-2 AND MALSR LIR STRUCTURES, STRUCTURAL CONFIGURATIONS"