The new Interceptor protective vest worn by American troops for the last few years proved, in Iraq, that it is bullet proof. But there is one problem that still has to be solved. The composite ceramic plates that are inserted in the front and rear of the vest to stop high powered rifle and machine-gun bullets, are heavy (nearly five pounds each) and brittle (often useless after taking, and stopping, a direct hit from a high speed bullet). The plates will sometimes shatter if dropped. The plates are also expensive, costing $500 each.. So research is underway to make the bulletproof plates lighter, cheaper and shatterproof.