Used RemotePilot101.com, ASA UAS Test Prep (book and app) and scored a 97. It was challenging. I was surprised at the score. Everyone claims to have the test bank, but after the two prep courses, and 3 or 4 other practice quiz sites, including 3DR, I didn't see more than about 10 questions that were represented in the prep courses or multiple practice quiz's. Fair warning... Don't just memorize answers, learn the material for the questions. Also, I had a bunch of questions on CRM, SMS, and Risk Management. Prep courses didn't delve real far into those areas.