jacquemoe - yes, the plexiglass insert is sized to your machine. Tony's Sewing Machines in Maine started making and offering these tables in just the past couple years when he felt there were few functional less expensive tables available. He has been in the selling and repair sewing machine business for many years - also sells industrial machines as well I believe. I think he has separated the two businesses but they are both his.
icandothat- I only needed the20 X 56 table as I had a small extension of my own that I put on the end (to the left). The friend I mentioned did get the 40 " extension that she has to the front of the table and it works very well for her.
My DH was willing to make a table for me to my specific needs/wants. After seeing this table, he felt the quality was so good for the price, it wasn't worth his making one if I liked this one.
I hope you get a chance to see before you buy.