Glass Floor Protector for office chair. Heavy tempered glass. Use over wood, vinyl, or carpet. The last carpet protector you will ever need. Advertised size on Amazon is 46 x 55, although it measures 46 x 53. Normal Amazon price is $136.99, which is what I paid for it. Now on sale for $103.34.
I strongly recommend buying from me rather than ordering online. It took three shipments before one arrived in one piece.