Abstract: A latch of the over center type for use inter alia in locking together surveyors rods in order to give reproducible measurements. The latch locks together a first axially slidable member (2) and a second axially slidable member (8) in overlapping disposition; it comprises a pair of latch supporting pivots (22) extruding from the first member, on a first common axis a pair of latch fulcrum pivots (26) extruding from the second member on an axis parallel to the first axis, a latch arrester (30) extruding from the first member, a latch body (16) having a face and sides (18) which extend to or past the latch fulcrum pivots (26) each latch side having an S-shaped recess (24) to engage the associated fulcrum pivot and an elongated slot (20) to engage the elongated latch support pivot. At least one of the sides has an edge protrusion (34) which must be snapped past the latch arrester (30) to complete the latch action.