I needed a way to extend the 30" gas cooktop cutout on my Corian countertop to accommodate a new 36" cooktop. After researching various options for cutting Corian online, it turned out that using a router with a spiral cutter was the best option. Since the countertop was already installed, it had to be cut from top to bottom. The down cut bit seemed to be the best as it minimizes any chipping of the Corian finish. I chose the Whiteside beat as it was highly rated. I'm glad I did. I used a plunge router for cutting as I thought it would be easier to control the cut. It was difficult to fit the straight edge template to the existing countertop as there was nothing to attach it to. I ended up making a loose cut and did it slowly to keep a straight line. This bit is very sharp and cutting went well. I did this in three passes to keep WOB to a minimum. A lot of chips and dust were generated when cutting Corian. Make sure you have a vacuum handy so you can see what you're cutting. After cutting, the drill is still sharp. In general I am satisfied with the purchase. The only difficulty in the rear was cutting the back wall of the fender. The router didn't have enough space to reach the end. I had to finish the last 1-2 inches of the cut with a carbide bladed multi tool. I'm very glad I didn't have to do the whole cut this way. It would take forever. The blade generates a lot of heat and melts the plastic.