Abstract: A playpen includes four posts, four rails installed between the posts, at least two stems attached to one of the rails and at least two positioning devices each attached to one of the posts for cooperating with the stems for movably installing the rail on the posts. Each of the related posts includes a groove for receiving one of the stems and a dent in communication with the groove. Each of the positioning devices includes a button movable across the detent and a latch including a first portion connected to the button and a second portion. The button is operable so as to move the latch between a locking position where the second portion thereof restrains the stem in the groove and a releasing position where the second portion thereof retreats from the groove.

Abstract: A playpen includes four posts, four rails installed between the posts, at least two stems attached to one of the rails and at least two positioning devices each attached to one of the posts for cooperating with the stems for movably installing the rail on the posts. Each of the related posts includes a groove for receiving one of the stems and a dent in communication with the groove. Each of the positioning devices includes a button movable across the detent and a latch including a first portion connected to the button and a second portion. The button is operable so as to move the latch between a locking position where the second portion thereof restrains the stem in the groove and a releasing position where the second portion thereof retreats from the groove.