This is a great product. it is simple, light and portable and I would highly recommend it to any drum user who is looking to get a great sounding kick with better mic placement.
The reason I bought this product was to be able to put a mic on the inside of the kick drum to get a better sound. The Bass Drum O's Cutter is one of the best ways, in my opinion, to get a clean and perfect circle cut in the front bass and with the moveable pin, it is easy to measure how big of a hole you want to cut. if your not sure on what size to go for or where to cut it as every place will give you a different sound, what I did was tape a washable marker or chalk to the top and trace out a few around the skin till you find a size and place that you think is the best for your kick drum. also when cutting get a large flat piece of cardboard to place your the skin so you can put as much pressure as you like on it and not damage your floor or table.
This is also a good product if you are a sound technician and you are working with a less experienced drummers I find that keeping a Bass Drum O's Cutter in your tool box is very handy for time like if you are working with a drummer and his bass drum could do with a bit of fixing up and they let you fix their kit (don't just start cutting holes in other people's drums without asking it doesn't go down well) having a Bass Drum O's Cutter with you means your not running around trying to find anything that is able to solve your problem
To further improve the acoustic of your bass drum I recommend the t.akustik Kick Drum Absorber it is one of the best products I have ever bought.