A power tool is provided with an adjustable handle assembly. In one aspect, the system includes an inner set portion adapted to fit into an ear canal. Machine-pressing of the machine-pressable chair cover drastically reduces the maintenance costs and time of the machine-pressable chair cover. The tube has a shape and rigidity sufficient to maintain a gap between the circuit components and the inner surface of the tube such that thermal expansion of probe components result in no physical stress to the circuit components.