Abstract: The present invention relates to a medical delivery comprising a) a housing (101) adapted to accommodate a drug in a drug reservoir (110) the housing (101) having an exterior surface defining at least one non circular section b) a drive mechanism for expelling doses of drug from the drug reservoir (110) and c) an operable control member (150) arranged at the non circular section of the housing the operable control member (150) being movable relative to the non circular section of the housing for altering a parameter relating to the operation of the medical delivery device. The operable control member (150) comprises a belt like structure arranged to move along the non circular section of the housing so that respective portions of the operable control member change radius of curvature as the respective portions move relative to the non circular section of the housing.