EXTRUDED FABRICATED ALUMINUM MATERIAL; 21 INCH BASE WIDTH; 5 FT HEIGHT TO TOP STEP; 5 HEIGHT TO TOP STEP IN FT; 250 LOAD RATING IN LB; 250 LB LOAD RATING; 35 INCH BASE SPREAD; APPLICABLE STANDARD ANSI A14.2, OSHA, UL; RATING TYPE I HEAVY DUTY