I have very thick chipboard that I use for books and this cut through it with no problems. I was amazed. It did take 2-3 passes on the trimmer, but it cut it clean. The trimmer locks down onto your paper/chipboard and it will not move as you cut. Best trimmer I have found to cut thick items.
I love this trimmer! It cuts through chipboard and multiple sheets of cardtock like butter. I make a lot of books with my zutter so this saves me so much time and was worth the price (which I was worried about).
I have the larger 15" version of this trimmer and I absolutely love it. I needed something that could cut cleanly through heavy weight chipboard and this does the job with ease. Very highly recommended!