once selected the candidates may choose to advance to the SF selection, which takes place twice a year in the spring and the autumn term. There are fifteen Para (SF) battalions and soldiers are selected accordingly. An example of this would be the 10 Para (SF) who are also known as Desert Scorpions. The probation period for this unit is three-months and the probationers are selected accordingly for desert warfare. The 9 Para (SF) who specialise in Mountain warfare go through a six-month course at the Special Forces training school in Nahan, Himachal Pradesh, which is followed by further specialised selection. This concept of geographical specialisation was eventually modified and each Para (SF) battalion is now trained to operate in various terrains and climatic conditions. Soldiers of the Indian Army can volunteer for the course irrespective of rank. Depending on the battalion, the probation period is for three months which doesn't include additional time for specialized skills. Over the probation period, all soldiers are stripped of their ranks, including officers, and are known as probationers or probies. A probationer may opt to leave anytime during the course. The completion rate is under 12-15 per cent and this slightly high completion rate is because many probationers are drawn from their regimental battalions. Every Special Forces operator specialises in various skills such as weapons handling, demolition, navigation, communication, and medical. PARA (SF) usually work in small teams of only six men, focusing on strategic reconnaissance, surveillance, target designation (RSTAD), hostage rescue and direct action (DA) tasks, and are selected and trained accordingly. Those who complete the probation period and are inducted into the Para (SF) undergo further selection and training, but to earn the Balidan Badge or "Badge of sacrifice", they have to further survive being deployed in active operations in hostile zones. Training centres and courses Commando Training Wing, Belgavi, Karnataka 4-week High-Altitude Commando Course, Parvat Ghatak School in Tawang, Arunachal Pradesh Desert Warfare School, Rajasthan High Altitude Warfare School (HAWS), Sonamarg, Kashmir Basic Combat Divers Course, Indian Navy's Diving School, Kochi Counter insurgency, at the Counter Insurgency and Jungle Warfare School (CIJWS) in Vairengte, Mizoram Special Forces Training School, Bakloh, Himachal Pradesh Basic Parachuting and Combat free-fall training (HAHO and HALO) at the Parachute Training School, Agra & Army Airborne Training School, Agra 90-day Selection Some of the training during the 90-day selection includes: Day 1 to 35: The first