Its self-supporting metal structure has the following characteristics:
- One fund drawn in single step with steel sheet 15/10 mm thick, watertight
- Two reinforcing bars (15/10 mm thick) spot welded on the bottom fund, each one with two anti-friction roller supports.
- Two side and two end walls (15/10 mm thick), stamped and assembled to form a truncated pyramid shape with rounded corners
- Stiffening ringĀ  formed by four joined bars 20/10 mm thick, each one assembled on one wall
- Two central reinforcements (one for each short wall) with its DIN reinforcing pillar complete with sliding roller made in Teflon

The additional ring is riveted to the main container and it can have a maximum height of 42 cm.