The 9K31 Strela-1 (arrow) is a highly mobile, short-range, low altitude infra-red guided surface-to-air missile system. "9K31" is its GRAU designation. Its NATO reporting name is SA-9 "Gaskin".

Each TEL consists of two pairs of ready-to-fire 9M31 missiles mounted in boxes on either side of a turret on a BRDM-2 amphibious vehicle.

The missiles used in this system were developed alongside the prolific Russian MANPADS 9K32M "Strela-2" (NATO designation SA-7 "Grail") in the 1960s and first became operational in 1968.

Each missile weighs 30 kg (66 lb), is 1.8 m (6 ft) long, flies at an average of around Mach 1.5 with a top speed of Mach 1.8 and carries a 2.6 kg (5.7 lb) warhead with proximity and contact fuses.

Propulsion is by a single-stage solid fuel rocket motor. Targets can be travelling at up to Mach 1.

Due to the low frequency, first generation lead sulphide uncooled (PbS) infra-red seeker on the missiles, engagement range is actually greater when the missile is used in a tail-chase engagement, i.e. fired at an aircraft flying away from the launcher.

In this case effective range might be as long as 11 km (6.8 miles). Similarly, when engaging an aircraft head-on, effective range is below the maximum specified above.

The 9M31M/SA-9B missile's seeker is improved, including a cooling system, which partially accounts for the better range figures. The new seeker is able to detect radiation in the 1-5 µm range, an improvement over the old seeker with its 1-3 µm range.

Steering is performed by canards and tail-fins with proportional guidance based on the information from the seeker. The rocket motor is a solid fuel, dual-thrust type which only fires after the missile has been ejected from the launcher.