A syringe and grid interface provides for improved wear and performance characteristics by providing compliant contacts on the grid. The rental-item providing machine makes a credit inquiry about the users. The trailer-conveying apparatus formed by the trailer of the present invention and winches occupies less land, being low in cost, simple in structure, reasonable in design, advantageous to shield the radiation, and easy to be maintained. Configuration parameters remotely managed by the network include device addresses, transmission credit values, upstream channel assignment and upstream transmit power level.