A retaining assembly (2) for a footwear production conveyor system, the retaining assembly comprising a base (4) having a first side (8) having a last portion and a second side (6) configured to be connected to a vehicle of said footwear production conveyor system, a locking device configured to have a first position where a last is retained relative to the locking device, and a second position where said last is released relative to the locking device and/or vice versa, a passive opening mechanism configured to be positioned in a predefined region of the footwear production conveyor system where the opening mechanism is configured to interact with the locking device to manoeuvre the locking device from its first position to its second position, and/or vice versa, wherein the locking device comprises at least a first locking mechanism (26) having a first locking part (36) which is connected to the last portion of the base, and a second locking part (38) that is configured to interact with the opening mechanism.