Mountain Equipment Tupilak Packs all come in a single back length which is 47cm (19"), using the length of the EVA back panel as the back length. This back length is designed to fit as many people as possible and still carries well at the extremes of its range (packs have tested by users that are over 6ft and some just over 5ft, male and female). However, if you are very short or very tall, they may not be suitable for you. They are best tried for size fully laden.