D3O® Viper 1 Back Impact ProtectorStandard back size protector supplied with most men's jacketsAdvanced, patented polymer, CE-rated D3O® impact protectorD3O® impact protectors utilize intelligent Molecules that lock together on impactBecause of this, the impact protectors can be made thinner and lighter, making a jacket more comfortable and easier to wearDecreased size does not come at the expense of impact protectionStandard size back protector supplied with all men's jackets