I-BEAM SIDE RAIL TYPE; EXTRUDED FABRICATED ALUMINUM MATERIAL; 17-1/2 INCH BASE WIDTH; 250 LOAD RATING IN LB; 250 LB LOAD RATING; PARALLEL BASE TYPE; 2 SECTION(S); 1-3/4 INCH FLAT D RUNG SIZE; WERNER. BRAND; APPLICABLE STANDARD ANSI A14.2, OSHA, UL