▁the ▁shield ▁without ▁ob struct ing ▁vision . ▁Similarly , ▁metal ▁ri ot ▁shield s ▁often ▁have ▁a ▁small ▁window ▁at ▁eye ▁level ▁for ▁this ▁purpose . ▁These ▁ri ot ▁shield s ▁are ▁most ▁commonly ▁used ▁to ▁block ▁and ▁push ▁back ▁crow ds ▁when ▁the ▁users ▁stand ▁in ▁a ▁" wall " ▁to ▁block ▁protest ers , ▁and ▁to ▁protect ▁against ▁sh rap nel , ▁project iles , ▁mol ot ov ▁co ck t ails , ▁and ▁during ▁hand - to - hand ▁combat . ▁ ▁The ▁second ▁type ▁of ▁modern ▁police ▁shield ▁is ▁the ▁bullet - res istant ▁tact ical ▁shield . ▁These ▁shield s ▁are ▁typically ▁manufact ured ▁from ▁advanced ▁synth et ics ▁such ▁as ▁Ke v lar ▁and ▁are ▁designed ▁to ▁be ▁bullet proof , ▁or ▁at ▁least ▁bullet ▁resist ant . ▁Two ▁types ▁of ▁shield s ▁are ▁available : ▁▁ ▁Light ▁weight ▁level ▁III A ▁shield s ▁that ▁stop ▁hand ▁guns ▁and ▁subm achine ▁guns . ▁ ▁He avy ▁Level ▁III ▁and ▁IV ▁shield s ▁that ▁stop ▁rif le ▁r ounds . ▁ ▁T act ical ▁shield s ▁often ▁have ▁a ▁firing ▁port ▁so ▁that ▁the ▁officer ▁holding ▁the ▁shield ▁can ▁fire ▁a ▁weapon ▁while ▁being ▁protected ▁by ▁the ▁shield , ▁and ▁they ▁often ▁have ▁a ▁bullet proof ▁glass ▁view ing ▁port . ▁They ▁are ▁typically ▁employed ▁by ▁special ist ▁police , ▁such ▁as ▁SW AT ▁teams ▁in ▁high ▁risk ▁entry ▁and ▁sie ge ▁scenarios , ▁such ▁as ▁host age ▁rescue ▁and ▁bre aching ▁gang ▁comp ounds , ▁as