Abstract: A folding collapsible stroller that includes a pair of constraint devices to hold the stroller in an operative position. The constraint devices have a sector groove and a deep blind hole at a top side thereof. A projecting portion is situated between the sector groove and the blind hole. A projecting rod is inserted into the sector groove to secure the constraint device in the closed position. The projecting rod is moved into the blind hole to allow the constraint device to engage the top end of the side frame to hold the stroller in the operative position.