Augusta National prohibits the use of a few different practice tools that are allowed on most other practice putting greens. Things like:

• Stimpmeters
• Sam PuttLab
• Launch monitors
• Perfect Putter Training Aid

Essentially, any tool that can help players, caddies or coaches measure the exact speed or slope of the greens. Because when they know that, understanding the break stops being an art of estimation, and starts being a basic measurement process

It presents one of the more unique preparation challenges that players have to adapt to this week.