The photo shows a Yachttech Spars and Rigging Systems tang bolt replacement system.  The large bushings are made of aluminum and have a much greater bearing surface against the mast then the old compression sleeve.  This also allows the old and possibly out-of-round hole to be enlarged.  The inner bushing and custom double-ended bolt are made of stainless.  Galvanic activity is minimized.  The threads are cut to the exact depth so that when the nuts are tightened down, the tangs are held against the mast at the precise measurement required.

Yachttech is a leading manufacturer of aluminum sailboat masts, booms and rigging equipment . They are located in Sidney, B.C. Canada.  These bolts can be obtained directly or through Brion Toss Rigging.