The Autoriti Monetari Brunei Darussalam and the Monetary Authority of Singapore will each issue notes of 50 ringgit (BND50.6) and 50 dollars to (SGD50.4) commemorate the 50th Anniversary of the Agreement by which the Bruneian ringgit and the Singaporean dollar are interchageable. The notes are issued in limited quantities, with the dateline to order them is July 12. 

Courtesy Gabriel’s Numismatic Market 

Source  Monetary Authority of Singapore