HAY AAC53 About A Chair - Gas LiftPerhaps the most functional chair of the Hay About A Chair family, the AAC53 features a five legged castor base equipped with a semi automatic gas lift that can adjust the seat height from 42 to 56 cm. Just like the rest of the About A Family, the aluminium base can be combined with the a wide choice of colours and fabrics that gives you further options to adapt the chair to whatever environment you need the chair to fit into.