EXTENSION SPRINGS End hook types include "German" "English" closed, half-closed, elongated and double Wire Diameter: from 0.1 mm to 16 mm Wire Shape: circular, square or rectangular section Wire Materials include: patent carbon steels, stainless steel, alloys, pre-tempered and zinc-coated wire, bronze, beryllium copper etc. Every design requirement can be met on request: springs can be galvanised, burnished, phosphor-coated, shot-peened, electro-polished, oiled, dehydrogenated etc.