Motorcycle garments must have armour on the inside at major impact regions such as shoulders, elbows, hips (with the exception of Class A or B) and knees. Optional protection may be present at the back, chest and lumbar. The European Standards for these protectors are EN 1621-1:2012, EN 1621-2:2014 and EN 1621-3:2018. Motorcycle armor was originally made from high density foam or foam backed hard polymers for impact absorption, and designed to prevent or reduce injury by spreading and dampening impact and shear strains to the wearer. However, viscoelastic materials are increasingly being used because they combine being soft to wear with significant impact absorption. In Europe, by law, armor has to have a CE mark. CE-marked armor comes in two levels, with Level 2 providing greater protection. There are also motorcycle jackets that use an airbag system, which deploys in the event of an accident, inflating to protect the riders neck, torso, and lower back (see also Airbag and Air bag vest). Airbag protection has been used in MotoGP since 2007, and has been compulsory since 2018.