A substance delivery device for delivering a substance from a container, the device comprising: a body; a plunger which is movable with respect to the body so as to expel at least a portion of a substance from a container, wherein a degree of movement between the plunger and the body determines an amount of substance that is delivered; an instance of one or more co-operating features (104,105) associated with the plunger and a corresponding instance of one or more co-operating features (104,105) associated with the body, wherein there are plural instances of said one or more co-operating features associated with at least one of the plunger and the body, the plural instances of one or more co-operating features associated with one of the plunger and the body each comprising one or more tracks and the or each track of a first instance of the one or more co-operating features is relatively long compared with the or each track of a further instance of the co-operating features, whereby co-operation between different instances of co-operating features (104,105) allows different ranges of movement between the plunger and the body, wherein relative rotation of the plunger and the body determines which instance of one or more co-operating features (104,105) associated with the body or the plunger is selected for co-operation with the corresponding instance of at least one co-operating feature associated with the other of the body and the plunger a trigger mechanism; a latch member latched in a stationary position at least along the longitudinal axis of the device before use; a lockout shroud being moveable along the longitudinal axis relative to the latch member, wherein user manipulation of the trigger mechanism causes the latch member to become unlatched and able to move along the longitudinal axis and to enable movement of a plunger relative to the body, and in a first forward position of the lockout shroud along the longitudinal axis relative to the latch member, the lockout shroud prevents the trigger mechanism from unlatching the latch member, whereas in a second rearward position the lockout shroud allows the trigger mechanism to unlatch the latch member. a body; a plunger which is movable with respect to the body so as to expel at least a portion of a substance from a container, wherein a degree of movement between the plunger and the body determines an amount of substance that is delivered; an instance of one or more co-operating features (104,105) associated with the plunger and a corresponding instance of one or more co-operating features (104,105) associated with the body, wherein there are plural instances of said one or more co-operating features associated with at least one of the plunger and the body, the plural instances of one or more co-operating features associated with one of the plunger and the body each comprising one or more tracks and the or each track of a first instance of the one or more co-operating features is relatively long compared with the or each track of a further instance of the co-operating features, whereby co-operation between different instances of co-operating features (104,105) allows different ranges of movement between the plunger and the body, wherein relative rotation of the plunger and the body determines which instance of one or more co-operating features (104,105) associated with the body or the plunger is selected for co-operation with the corresponding instance of at least one co-operating feature associated with the other of the body and the plunger a trigger mechanism; a latch member latched in a stationary position at least along the longitudinal axis of the device before use; a lockout shroud being moveable along the longitudinal axis relative to the latch member, wherein user manipulation of the trigger mechanism causes the latch member to become unlatched and able to move along the longitudinal axis and to enable movement of a plunger relative to the body, and in a first forward position of the lockout shroud along the longitudinal axis relative to the latch member, the lockout shroud prevents the trigger mechanism from unlatching the latch member, whereas in a second rearward position the lockout shroud allows the trigger mechanism to unlatch the latch member.