I currently work at an orthopedic company. We recently had to make an update to insert a class III PMA logo for all level III medical device. Since I had to go through several devices, I did not want to ask my manager about each one and tried to figure them out myself. I actually found the FDA website to be useful, it has a section on how to determine classification. From here you can either use the classification database (where you can search for part of the device name) or the device panel (listed by speciality).