A prestige scale for boats, comparable to that of 1:32 for fighter planes, is 1:72, producing huge models, but there are very few kits marketed in this scale. There are now several clubs around the world for those who choose to scratch-build radio-controlled model ships and submarines in 1:72, which is often done because of the compatibility with naval aircraft kits. For the smaller ships, plank-on-frame or other wood construction kits are offered in the traditional shipyard scales of 1:96, 1:108, or 1:192 (half of 1:96). In injection-molded plastic kits, Airfix makes full-hull models in the scale the Royal Navy has used to compare the relative sizes of ships: 1:600. Revell makes some kits to half the scale of the US Army standard: 1:570. Some American and foreign firms have made models in a proportion from the Engineer's scale: "one-sixtieth-of-an-inch-to-the-foot", or 1:720.