LEGO Set identification?
It appears to be part# 64261 from set# 8983, "Vorox".  



https://www.bricklink.com/v2/catalog/catalogitem.page?P=64261&amp;name=Bionicle%20Mask%20Vorox&amp;category=%5BBionicle,%20Kanohi%20Mask%5D#T=C&amp;C=2  

  

https://www.bricklink.com/v2/catalog/catalogitem.page?S=8983-1#T=S&amp;O={%22iconly%22:0}   

Instructions can be found here:
https://www.lego.com/biassets/bi/4547677.pdf