A must if you want to up your game
This product is a must if you wish to have accurately-placed stitches.  Yes, it's a pain to place the guidelines on the canvas, but it's worth the pain.  Less pain for Aida, a bit more for linen.  With the guidelines in place, your chance of placing a stitch in the wrong part of the pattern is severely reduced, if not completely eliminated.  Your stitching enjoyment is greatly increased.
Because this product is impermeable, a needle cannot pierce it, and thread cannot go through it.  And when you finish stitching, it is the work of 2 seconds to remove the guidelines from the canvas.  
My only wish is to have thinner-diameter guidelines available for higher-count canvases (hint, hint).
by: Marjorie on 9/17/2020