From a news article:
On November 18th, 2004 it was announced that Thailand was to receive the remaining 7 RSAF F-16A/B's (3 Alpha models and 4 Bravo models). They were all handed over in the course of January 2005. Instead of a standard purchase between two governments, these airframes are donated by the government of Singapore to the Thai Air Force. In return the RSAF can train on the Thai air base of Udon Thani a number of days each year.