A directional input device , comprising: a base ; a head selectively connected to the base by a twist-lock mechanism, wherein the head and base define a center axis , the twist-lock mechanism including: a post protruding from one of the base and the head, oriented in the axial direction of the center axis, at least one flange protruding in a radial direction from the post, a receiver located in the other of the base and the head than the post, configured to receive the post and the flange, and an angularly oriented channel in the receiver configured to allow the post and flange to rotate into the channel and capture the flange in the axial direction; and a rotational lock between the receiver and the post that limits and/or prevents rotation of the post relative to the receiver when in a locked position, wherein the rotational lock includes at least one axial protrusion , a complementary axial detent , and a ramped recess angularly adjacent to the axial detent, wherein relative rotation of the post and the receiver around the center axis causes the ramped recess to contact the protrusion and apply an axial force as the protrusion travels up the ramped recess in the locking direction to elastically deform at least a portion of the directional input device, until the protrusion reaches the detent , when the protrusion will elastically restore and rest in the detent in locked position, wherein the rotational lock requires a greater unlocking torque than a locking torque. a base ; a head selectively connected to the base by a twist-lock mechanism, wherein the head and base define a center axis , the twist-lock mechanism including: a post protruding from one of the base and the head, oriented in the axial direction of the center axis, at least one flange protruding in a radial direction from the post, a receiver located in the other of the base and the head than the post, configured to receive the post and the flange, and a post protruding from one of the base and the head, oriented in the axial direction of the center axis, at least one flange protruding in a radial direction from the post, a receiver located in the other of the base and the head than the post, configured to receive the post and the flange, and an angularly oriented channel in the receiver configured to allow the post and flange to rotate into the channel and capture the flange in the axial direction; and a rotational lock between the receiver and the post that limits and/or prevents rotation of the post relative to the receiver when in a locked position, wherein the rotational lock includes at least one axial protrusion , a complementary axial detent , and a ramped recess angularly adjacent to the axial detent, wherein relative rotation of the post and the receiver around the center axis causes the ramped recess to contact the protrusion and apply an axial force as the protrusion travels up the ramped recess in the locking direction to elastically deform at least a portion of the directional input device, until the protrusion reaches the detent , when the protrusion will elastically restore and rest in the detent in locked position, wherein the rotational lock requires a greater unlocking torque than a locking torque. <EOS>