An earpiece for a hearing device is provided with a high retaining force in an ear shell in a repeatedly detachable manner. An analog or digital video signal is conveyed to an operator of the apparatus through the visual display. A patella may be offset from its normal position with an inner side of the patella facing inward during cutting of a bone with a cutting tool. The multi-layer rust prevention film can be applied to various electronic components including computer equipment, communication equipment, or the like. The mapping may include assigning each application component to a distinct virtual machine, which acts as a container for its assigned component. In some embodiments the distal end is contoured to also accommodate the anatomical structure of the patient so that a cylindrically shaped, funnel shaped, ovoid shaped dilator retractor can be sloped or tunneled to accommodate the bone structure of the patient or provide access for implants.