Instruct: Classify Amazon reviews into positive or negative sentiment
Query: useless

This is one of the myriad of contraptions aimed at making something that require skill and patience simple and easy. You might as well light your money on fire. Applying the masking liquid takes almost the same amount of time and skill that it would to cut in with a brush. Save your money. Buy a roll of bluet tape, there's no way to paint around glass without being patient and careful.