12×12 mat —
9.00″ × 11.11″
Unglued selflocking tray with 4 double walls; locking flaps system with fold over ends with nib locks. All four walls fold back down inside themselves. The end walls carry a bump on the folded edge that tucks behind a tongue slit into the base; the side walls carry past each corner into a flap that folds in behind the end wall. The catalogue draws that flap at the full wall height; here it also stops short of its opposite number, which a tall narrow tray outgrows. ECMA catalogue, p.36 ↗