Looked to be made of clear Perspex , the shield is strapped to Oxenford 's non-dominant signaling arm .
Looked to be made of clear Perspex , the shield can be used to parry and block shots fired back in the umpire 's direction .
Looked to be made of clear Perspex , the shield is strapped to Oxenford 's non-dominant signaling arm , and can be used to parry and block shots fired back in the umpire 's direction .