“Eiger Tools’ wallet-size caliper is thinner than most credit cards and can easily measure an object’s inside or outside diameter. It’s ideal for measuring nuts, bolts, and pipes and can also measure curved surfaces up to 10 cm in circumference. The card is machined from stainless steel and includes a brass carrying case to protect…” (via The Awesomer)
Eiger Tools Card Calipers Hobbyist’s Tool
