The Full form of SI is Sub-Inspector. The SI or Sub-inspector is a rank used in South Asian countries extensively; i.e. in the Indian Police, Bangladeshi Police, Sri Lankan Police and Pakistani Police. It is primarily based on the British model. Generally, a Sub-Inspector is in command of a police station. He ranks above an ASI (Assistant Sub-Inspector) of police. The rank insignia for a SI is two stars and a red and blue striped ribbon at the outer end of the shoulder straps. A Sub Inspector is the in-charge of a police station and is responsible for the police administration of his charge.
The duties of SI are set out in state and Indian police acts. The SI/SHO is also responsible for the law and order in his jurisdiction. Although Police constables below the rank of SI do not generally carry firearms on regular duty as they are available at police stations. Officers at the level and above the rank of SI are authorized to carry a side arm, generally a Glock 17 or a Pistol Auto 9 mm 1A. The eligibility required to apply for the position of ASI and SI, is 10+2 (Intermediate) or equivalent from a board or university recognized by the state or central government.