Abstract: A security device (10) to releasably secure articles in a queue, row or stack has a body (11, 12) to be clamped on one of the articles by a loop section (14) and lugs (17). A key (26) attached by a chain or cable to a second device (10) is received in a slot (30, 31) in the body and is releasably engaged by a peg (39) on a pivotally mounted operating arm (34), in a cavity (29) of the body entering a slot (27) in the key (26). The key (26) can only be released when a coin or token is received in a coin holder (47) in a pusher unit (48) which advances a tongue (40), the nose (41) of which engages a cam face (42) on the operating arm (34) to move the latter to release the key (26). The pusher unit (48) can only be moved to recover the coin or token from the coin holder (47) when the key (26) has been reinserted in the body and engaged by the operating arm (34).