It takes six months of specialised training to be selected for the elite Airport Security Unit. The training for this unit, which is marking its 30th anniversary, is the second toughest, after the special duties squad - the force's equivalent of a special weapons and tactics (Swat) team. And because the officers carry more than 13kg of weapons and equipment on their belts, physical fitness is vital. 'The fitness standard is stringent, and it is the foundation for this unit,' said Chief Inspector Clement Lai Ka-chi, the unit's officer in charge. Applicants have to complete 18 pull-ups and meet other fitness requirements to advance in the selection process. That is compared with the standard for the force's general recruitment - five pull-ups to be an inspector and seven to be a constable. 'The six-month fitness training is a guide to those who wish to join the unit,' Mr Lai said. Afterwards, 'officers have to attend a training session at the airport once a week, which prepares them for the other recruitment hurdles'. Those who advance then receive training in the use of weapons and equipment. 'Knowledge on new threats such as biochemical weapons is also included in our training,' Mr Lai said. Communications equipment has also been upgraded, and officers now carry first-aid kits on their belts. About 70 officers apply annually, but only 15 to 20 are selected to join the unit, the chief inspector said.