Watch List notes:

Charles II (1660-1685), Sixpence, 1675 over 4, laureate and draped bust right, rev. four crowned shields crucifor, four strings to harp, edge obliquely milled, 3.02g, 6h (Bull 568; ESC 1514; Spink 3382), good very fine.
Bull lists three strings, but a faint but clear fourth string, which appears on many examples, can be seen as you turn the coin.
Estimate: £150 - £200