This is my second LensCoat for a 300 IS F4 lens, one for my lens one for my son's. I also have these coats on my 400 and 500mm lens. All and all a very good product. One suggestion would be to "firm up" the stitching at the seam ends as the stitching starts to fray from rubbing due to repeatedly putting the lens into a tight fitting enclosures in a commonly used LowePro backpack. Otherwise very happy with this product..