Maun safety rules metricimperial 300mm maun 1774 300 this 300mm safety rule from maun is a handy tool with a unique m profile designed to keep fingers well away from any knife edge when used for cutting or scoring card etc manufactured to a high standard with stainless steel to give a long corrosion free life and equipped with metric scales the rule is ideal for both hobby and craft work in the educational field maun 1774 300 safety rule 300mm metric