12×12 mat —
10.70″ × 9.91″
Unglued selflocking tray with 2 double walls; locking flaps system with fold over ends with nib locks; tuck in flap cover system. B20.01 with a lid. The side walls fold back down inside themselves and lock behind tongues slit into the base, trapping the end walls' corner flaps; a full-size lid hinges off the back wall and tucks in at the front, its outer corners rounded. The catalogue draws those corner flaps at the full wall height; here each stops short of its opposite number, which a tall short box outgrows. ECMA catalogue, p.39 ↗