The Artco Bell D-Series Swivel Stool were designed to embrace the lab environment with pneumatic seat height adjustment, free-rolling casters, and comfort foot ring. D-Series Swivel Stools are available in an adjustable seat height of 23.5" - 33.5" with A and A+ sized shells. A+ sized shell offers 30% more surface area than the industry standard A size. Shell is one-piece, injection-molded polypropylene with anti-static additive. Color is dispersed across the polypropylene for an even appearance. Enhanced waterfall front edge and biometric design allows comfortable seating. Fifteen integrated wrap around ribs are provided for shell strength. Both sides of shell are textured and constructed with a handle in the upper portion of the shell with smooth edges for ease when carrying. A pneumatic adjustable column assembly is attached to the base and seat support. Seat supports are two steel tubes with end closures welded to two die formed seat brackets punched for concealed rivets. The one-piece shell is supported at the intersection of the seat and back with a die formed mounting plate, welded to the seat assembly and riveted to the lower flanges of the shell to prevent excessive flexing of the back. Adjustable 18"-diameter foot ring located on the column assembly. Base is made of glass filled nylon and receives the adjustable column assembly and five nylon twin-wheel free-rolling casters.