Designed to fit most standard diameter gas cylinders (48mm and 50mm),
 this unique foot ring can be added easily at any time without taking the chair apart.
Left and right halves fit firmly together and can be set at any height.
made from durable reinforced nylon.

CK55 Height Extension Kit
These convenient height extension kits easily convert Alvin's office-height chairs into draftingheight models. Each kit includes a strong cylindrical steel shaft with tapered end to lock into the chair base. Adds approximately 7½" to the height of the chair. Footring models can be adjusted vertically and then locked at the desired height. It is recommended that extension kits be attached when the chair is first assembled. All three extension kits fit the following chair models: CH277, CH290, CH444, CH555, DC205 and DC207B. Only CK38 fits models CH112 and CH222.