RECESSED Ceiling Mount Edge Lit Exit Sign Red LED with Battery Backup - Single Face - Adjustable Arrows

are the arrows removable?

Can this work work solely on battery power or does it need to plug into an active electric unit?

What is the lenth of the fixture also are the letters 8 inch. Nyc approved

Regarding the esw-elr-z. chevrons are remiovabe? this includes back box for ceiling mount? since it is clear exit reads backwards from rear of sign?