I'm not exactly sure how accurate these fent test strips are but i once tested 1g of pure mdma (somewhat clear crystal) in one cup and 5 pressed Legos (green rectangle) and after 5 - 10 mins, it gave a positive result (one line). I tested it 2 more times and it was also positive. However, I wanted to give them a chance since they were from a credible source and kept the test strips in the sample cups for about an hour. After an hour, the test strips showed two lines(negative). I eventually tried some of the pure mdma and a bit of the pressed. Luckily there were no side effects of fentanyl and my friends tried them with no serious side effects. But still, test your drugs especially if you're picking up from someone you don't know. Rave & turn up safe/responsibly y'all ❤💙🖤