During EDEX 2021, Larsen & Toubro Defence unveiled a model of SOV400 midget submarine, the entity is a Larsen & Toubro group company that has played an important role in the realisation of India's first indigenously designed nuclear submarine.

The SOV400 is a special ops diesel-electric midget submarine, designed and developed by L&T Defence.

SOV400 is primarily meant for deployment and recovery of special forces while being submerged up to 40m. Its unique "Moon Pool" enables quick release and recovery of marine commandos, while its two 4-men Swimmer Delivery Vehicles insert them deep inside enemy coastlines. In lieu of the SDVs, the submarine can carry two commando containers.

It is fitted with twin torpedo tubes that can launch heavyweight torpedoes for attacks in shallow waters or in self-defence. The SOV400 is fitted with a modern conformal array sonar and advanced radio-electronic sensors for detection, surveillance, communication and interception which provide tactical information for the command through an integrated combat management system.

The submarine is powered by two groups of VLA batteries with 112 cells each.