Hello- I have tried the vacu inserts and install them into balls for some customers. When installed it allows a little bit of room for swelling and always seems to feel snug. To get an idea of what it would feel like you can get an insert that is 1-2 sizes smaller then what you currently use right now. Then without putting it in the ball push your finger into it. The grip expands around your finger. That is how this works and the "snug" or "vacu" feeling you will get. Hope this helps, Glen