Alera Elusion Series Mesh Mid-Back Multifunction Chair, Supports Up to 275 lb, 17.7" to 21.4" Seat Height, Black

Is the alera el4215 elusion series mesh mid-back multifunction chair, black leather real leather, pu leather or bonded leather?

Can chair be used without rollers?

Are the arms removable?

Anyone else have issues with the back of the chair dropping to seat? My chair is about a 1/2 year old and I cannot get the back rest to stay put now.