Spectra Shield is a composite material (specifically, an ultra-high-molecular-weight polyethylene (UHMWPE) fiber) used in bulletproof vests and vehicle armour. It is manufactured by Honeywell. Spectra is a fiber offered by Honeywell, and "Shield" is their patented process for using resin[1] and a "plastic film"[2] to bind multiple overlapping layers of Spectra, without having to have them be woven together.
Other popular fibers with similar uses are aramid (Kevlar or Twaron) and Dyneema (another UHMWPE).