For reasons that I cannot explain, the 39 degree DHS Hurricane 8 sheet that I used weighed significantly more than the 40 degree version. Batch inconsistency? Thicker sponge? I don’t know, but it sure is heavy! I found shots from mid-distance to be a little easier to execute with the 39 degree rubber relative to the 40 degree rubber. However, the differences between the mid-hard and hard versions are minor, less than 5-7% in my opinion. The 39 degree version is slightly softer and bouncier than the 40 degree version, meaning that looping requires a little bit less effort, which I actually think is a disadvantage, as full effort shots now have an increasing probability of going long. Click for our full review.