A hockey helmet (20) comprising a front helmet portion (22) and a rear helmet portion (24) disposed to be moveable relative to each other so as to define an internal cavity of varying volume, a securing member (26) being mounted to a location on the front helmet portion (22) adjacent the temple thereof, the securing member (26) being slidable between a first or open position and a second or closed position, the rear helmet portion (24) having a restraint (28) configured and disposed to be complimentary to the securing member (26) such that when the securing member (26) cooperatively engages the restraint (28), the relative displacement of the front helmet portion (22) and the rear helmet portion (24) is inhibited. The restraint (28) comprises a number of positions in which the securing member (26) can be cooperatively engaged such that the volume of the helmet (20) may be modified.