From the manufacturer:
Air Lift Thrones are the next evolution in DW throne technology. Combining the workhorse features of DW’s 9000 line of thrones, Air Lift thrones also include a sturdier quad-leg folding base, and effortless pneumatic height adjustment. The 9120AL design includes an optional backrest (sold separately) for those players that desire more support. Also Available in 24K Gold.