Airlift Thrones are the next evolution in DW throne technology. Combining the workhorse features of DWs 9000 line of thrones, Airlift thrones also include a sturdier quad-leg folding base, and effortless pneumatic height adjustment (U.S. Patent No. 7,718,878). The 9120AL design includes an optional backrest (sold separately, and exclusive to the Airlift model) for those players that desire more support, while the 9100AL incorporates a more traditional seat top. [20" min / 27.5" max height] The Pneumatic Height Adjustment allows quick and easy adjustment in seconds. (U.S. Patent No. 7,718,878) The Sturdy 4-leg Base keeps you planted. The Special Foam Combination provides superior stability and comfort. The Backrest (optional) works with all Airlift thrones.