Six matched pairs of parallels, 4140 hardened to 42 to 45 Rockwell, ground on our surface grinder and matched within two tenths across each pair. Heights from half an inch to three and a quarter, all six inches long and an eighth thick. They come in a wood block we make from shop scrap. These are not import parallels. We grind them ourselves when the machine is warm and there is a gap between jobs, so quantities are whatever they are that month. Every pair is checked on the granite with a tenths indicator and the check sheet goes in the box. If you want a nonstandard height added to the set, say so at checkout and we will grind it into the same batch for no extra charge as long as it is under four inches.