Connector assembly

A connector assembly 100 for electro-mechanically connecting downhole measurement probes, comprising: a first housing 106 having a bore 154 which receives a contact plug 134, the contact plug having a first end 170 with one or more contact portions, and an opposite second end 176 having an external circumferential boss 178 which locates the contact plug inside the first housing against a first threaded clamping ring 186; a second housing 104 receives a contact socket, the contact socket having a first end defining an opening 142, and an opposite second end with an external circumferential boss 136 which locates the contact socket inside the second housing against a second threaded clamping ring 144; the contact plug and contact socket each include means 140, 182 for locking against rotation; and the first housing is connectable to the second housing by rotation of an external connecting thread disposed on the second housing 130 with an internal connecting thread disposed in the bore of the first housing, when the contact plug is inserted in the contact socket the external and internal circumferential contacts are in electrical contact. Peg wrenches may be used to tighten the connectors. O-rings may be used.