Downhole tools, such as MWD modules (or components), may be coupled together with a coupler (or coupling device) having a shall housing with slidable electrical connectors disposed at each end. The electrical connectors may each be supported in connector housings disposed with springs or other movable devices. In a first position, the electrical connectors may extend past the ends of the shaft housing. The slidable connector housings allow the electrical connections to be made before the sleeves connecting (or mechanically connecting) the MWD modules with the coupler are begun to be threadedly attached with the coupler. Each of the connector housings may have a key configuration on their exposed end. The shaft housing may also have key configurations on its ends. The key configurations of the connector housings and the shaft housing may be configured to mate with compatible ends of MWD modules.