Designed for sculptors and turners, these calipers quickly find a role in any workshop. The smaller pair measures 245mm overall and has ratios of 1:1, 1.5:1, 2:1, 3:1 and 4:1. The large caliper is 510mm overall and has the same ratios as the small plus three more 1.25:1, 1.75:1, and 2.5:1.Both have a firm joint system where you adjust the amount of joint friction you want with the knurled brass thumbscrews. The arms are anodized aluminum. These are useful for scaling up or down as well as direct measurement transfer.