I-BEAM SIDE RAIL TYPE; EXTRUDED FABRICATED ALUMINUM MATERIAL; 19-1/8 INCH BASE WIDTH; 300 LOAD RATING IN LB; 300 LB LOAD RATING; PARALLEL BASE TYPE; 2 SECTION(S); 1-3/4 INCH FLAT RUNG SIZE; WERNER. BRAND; APPLICABLE STANDARD ANSI A14.2, OSHA, UL