Riding body protector or airbag?
The foam body protector protects as soon as it is worn, without anything needing to be triggered. It is classified under the European standard EN 13158 into three levels: level 3 offers the highest protection and is the one required for cross-country competitions. It is, however, warmer and stiffer than an airbag.
The airbag vest stays supple and light until it is triggered. It is attached to the saddle by a lanyard: when the rider falls, the lanyard pulls on the mechanism and a CO2 cartridge inflates the cushions that protect the neck, back and chest. In eventing, many riders wear both, with the airbag over the body protector.
After it has been triggered
An airbag that has inflated can be rearmed: screw in a new cartridge suited to your model and check the mechanism. Keep a spare cartridge in your show bag. Also check the length of the lanyard, because if it is too short, it will trigger the airbag as soon as you lean over to open a gate.
Before every ride
Check that the cartridge is screwed in properly and that the lanyard is attached to the saddle, in the direction indicated by the manufacturer. The Airbag Rider Kenji competition jacket hides the airbag inside a show jacket, an option for show jumpers who do not want a visible vest.
Choosing the right size
A body protector is chosen by chest measurement and back length. It should cover the ribs all the way down without interfering with your seat, and fasten without restricting your breathing. Airbags allow more leeway thanks to their adjustable straps, but should be tried on with the clothes you wear underneath: sweatshirt in winter, polo shirt in summer. Once in the saddle, the bottom of the vest should not knock against the cantle; have someone on the ground check this for you.
For the head, a riding hat in your size completes your protection. The rules on wearing them in competition are set by the Fédération française d'équitation.