Abstract: An adjustment device has a foot ring, a first positioning unit, a second positioning unit and a tightening collar. The foot ring has a mounting tube. The first positioning unit and the second positioning unit are mounted in the mounting tube and respectively have an inner threaded portion. The inner threaded portions are connected with each other to form a tapered threaded structure. The tightening collar is tapered and engages with the threaded structure formed by the inner threaded portions. The tightening collar and the positioning units match each by a taper ratio. Therefore, the adjustment device can be assembled around a leg tube firmly.

Abstract: A collapsible frame has four posts and at least two trays separately mounted on the posts. Each tray is composed of two longitudinal brackets, two transverse brackets, four connectors and multiple slabs. The brackets are mounted together to form a rectangular tray frame with the connectors, and the multiple slabs are mounted on the tray frame. Because the tray can be disassembled and reassembled, the collapsible frame could be packed in a small package. Therefore, the collapsible frame is convenient in packing and transportation.