Abstract: In a sleeve in a radio frequency filter at least one portion having a lateral dimension being smaller than the diameter of a screw to be threaded through the sleeve is provided. The portion is flexible in a radial direction, so that a screw threaded through the sleeve will be secured by a clamping force. The increased friction provided by this clamping force will hold the screw in a locked position. The magnitude of the clamping force can be varied within broad ranges, and the optimum force will be different for different applications. Thus, by using such a screw and sleeve, there is no need for a lock nut and the screw does not need to be readjusted once placed in the correct position.