are and notes). The MAS has said that the higher denomination notes (beyond $100) will continue to remain legal tender. Security features Previous security features in the Ship Series were carried over to the Portrait Series, and new ones incorporated into the banknote. The two most prominent security features are the engraved portrait of Yusof bin Ishak (which contains fine lines that are difficult for counterfeiters to mimic) and the Kinegram (a printed security hologram); MAS states that banknotes with missing or mutilated portrait or/and Kinegram command no value. Paper versions issued by BCCS features its logo and the face value, while those issued by the MAS features its logo with the Merlion (a mythical creature and national symbol) and the face value. Polymer versions of the banknote have the Kinegram replaced by an image of the Singapore lion symbol with the face value, showing the coat of arms of Singapore when tilted at varying degrees. Other security features include lithographic print (the resulting background hinders camera counterfeiting), anti-copying line structures, perfect registration, microprinting, asymmetrical serial numbers and windowed security threads (thin ribbons woven into the paper). Polymer versions of the banknote include two clear windows and other security features that substitute its paper version. Several features that are invisible to the naked eye appear when both versions of the banknote are exposed under UV light. Banknotes in general circulation The banknote's obverse features the portrait of the first president of Singapore, Yusof bin Ishak, and the reverse contain secondary themes that are linked to his life. The background on the obverse of the Portrait Series feature a different cowrie (sea snail whose shell was often used as currency) for each denomination. Signatories include BCCS chairman (and former Finance Minister) Richard Hu, Prime Minister (and former Finance Minister) Lee Hsien Loong, former Prime Minister Goh Chok Tong and Deputy Prime Minister and MAS chairman (also current Finance Minister) Tharman Shanmugaratnam. $2 banknote The money cowrie is featured on the obverse background of the banknote. Its reverse carries the theme of education and features three buildings, the Victoria Bridge School (now known as Victoria School), Old Raffles Institution Building at Bras Basah Road, and College of Medicine Building. Yusof received his primary education in 1923 at Victoria Bridge School, and his secondary education in Raffles Institution; His father, Ishak bin Ahmad insisted that his children be English-educated. He was also the