The SAR 21 ("Singapore Assault Rifle - 21st Century") is a bullpup assault rifle designed and manufactured in Singapore, chambered for the 5.56x45mm cartridge. First revealed and subsequently adopted by the Singapore Armed Forces (SAF) as its standard service weapon in 1999, it was designed and developed over a four-year period to replace the locally license-built M16S1 by the Ministry of Defence (MINDEF), Singapore Army and the former Chartered Industries of Singapore (CIS), presently ST Engineering Land Systems. Many of its design features are directly intended to address the weaknesses of the M16S1 as encountered operationally by some infantrymen. The rifle is being sold for export use aside from domestic use. In the United States, it was marketed by ST Kinetics via its American subsidiary, VT Systems. History and development Since the mid-80s, the SAF had an outstanding requirement to replace the M16S1, in use since 1973, in part due to licensing limitations that prevented Singapore from exporting the M16S1 or making new assault rifles based on it. In 1994, a proposal by the SAF was submitted to MINDEF for options to either procure new weapons (thought was given to purchase the M16A2) or to develop an indigenous rifle. On 19 November 2002, a patent was filed with the United States Patent and Trademark Office by Tuck Wah Chee and Felix Tsai with the patent number 6,481,144 B1. MINDEF officials, after consultations with the SAF, decided against buying weapons off the shelf as it would require soldiers to adjust to the new weapon, choosing instead to develop a weapon, designed and made specifically for ease of use by conscript soldiers of the SAF, who are mostly of slighter physiques. Coupled with the rising costs of maintaining the M16S1s, this made it more justifiable to develop a low-maintenance weapon. In 2009, criminal charges were filed against former Indian Ordnance Factory Board director Sudipta Ghosh for corruption, among the allegations were an improper partnership with STK over supplying Indian law enforcement with the SAR 21 Modular Mounting System. STK and several foreign firms involved were blacklisted by the Indian Defence Ministry. The SAR 21 is set to be replaced by the BR18 in the Singapore Armed Forces in the near future. Design The SAR 21's furniture is made of a rugged, high impact polymer, much of the manufacturing is done utilising CNC machines, with ultrasonic welding for the steel-reinforced receiver halves and