… bridges and bridge-sections, lock-gates, towers, lattice masts, roofs, roofing frame-works, doors and windows and …
Explanatory notes
… bridges and bridge‑sections, lock‑gates, towers, lattice masts, roofs, roofing frame‑works, doors and windows and … include clamps and other devices specially designed for assembling metal structural elements of round cross‑section … tapped holes in which screws are inserted, at the time of assembly, to fix the clamps to the tubing. Apart from the …