efficiency similarly link efficiency is a function of the material from which the electrodes and surrounding body are made experimentally it is found that pure lead and lead alloy coatings greatly improve link efficiency over steel or titanium also the choice of electrode edge shape and edge proximity to other sub structures and boundaries has link efficiency effects it is important to optimization of performance of the links to have awareness of and control over the above factors for the second mud pulser surface link embodiment fig4 a shows an implementation of an upper band electrode mounted on the surface link sub this electrode is only for one or two way communication with the lower sub of the short hop link referring to fig4 a the recessed band 20 is mounted in an insulating bed 30 and is electrically connected to a removable electronics interface 10 item 10 has standard threaded and connectored ends and is designed to accept a mud pulser or other surface communication means on the right side with sensor and control tools on the left item 10 consists of a central pressure barrel 10 a and an outer annular sleeve lob supported by three vanes which allow drilling mud to flow through the assembly.