Patent ID: 7617574

Claim:
A telescoping fastener comprising: a housing defining a vessel having a smooth, unobstructed interior surface; a plunger having a body movable in said vessel, said body substantially closing an end of said vessel to define with said housing a substantially closed vessel area, said body having a varying length in said housing upon movement of said plunger and having relief channels arranged along the direction of movement of said plunger and extending throughout the varying length of said body within said vessel to provide uninterrupted pathways between said plunger and said smooth, unobstructed interior surface of said housing; a port in said housing extending from an interior volume of said vessel to an ambient environment of said vessel; a debris removal extension projecting from said body into said substantially closed vessel area and configured for moving contaminant material in said vessel toward said port, said extension having a force concentrating tip configured for disrupting debris in said vessel; and the relief channels allowing unobstructed flow of liquids and debris around the plunger and through the vessel upon relative movement between the plunger and the housing.