looking for large cover glasses - (Oct/12/2012 )

What is the largest size (in diameter or length X width) of cover slips or cover glasses available to purchase ? I need the largest size possible to use in a slide culture plate.

The largest I have seen are as long and as wide as the useable area on an ordinary glass microscope slide.

22 x 50 mm is the largest I have seen. I buy from Marienfeld. You may want to look up for this company on Google.