This set contains 2 springs and 4 brass nuts for the Z-axis of a prusa-mendel Reprap Printer.
Running stainless steel nuts on a stainless threaded rod causes rapid wear and is highly prone to galling.
A much better solution is to use brass nuts on the stainless steel threaded rod with a light smear of grease for lubrication.
The springs are 12mm OD and made of 8 turns of 0.9mm zinc-plated spring steel wire. The free length is 30mm
The brass nuts are the same size as standard M8x1.25 full hex nuts. 13mm across flats and 6.4mm wide