Abstract: A snap hook for use in climbing, pot holing or similar activities, comprising a C-shaped body and an arm mounted pivotally about a pin positioned in the body. An end of the body and of the arm are complimentary shaped parts, male and female, respectively, the male part being T-shaped in a transverse section, the female part being of a complimentary shape; the two parts, male and female, are within the circumference of sections comprising the snap hook; and there is a peripheral clearance laterally and longitudinally between the two parts.