A kit of parts for assembling an adaptor for electrically connecting a surface mounted component to a perforated circuit board comprises a multiplicity of wire wrap contact pins each having, integral with the trailing end of the pin and extending laterally with respect to its axis, an arm which, when the pin is engaged in a hole in a circuit board, bears against a major surface of the board and constitutes a footprint of the adaptor. The multiplicity of wire wrap pins comprise at least two groups of wire wrap pins, the lateral arms of the pins of each group being identical to one another and the lateral arms of the pins of one group differing from the lateral arms of the pins of each other group. The lateral arms of the pins of the groups are of such shapes that an adaptor for any one of a plurality of surface mounted components having arrays of leads differing from one another can be assembled on a circuit board by selecting appropriate pins, inserting the pins in holes in a circuit board and positioning the lateral arms on a major surface of the board in accordance with a predetermined pattern.