Illicit drug overdoses are a leading cause of death in the US. Even with psychedelics (which from a medical perspective have a lower potential to cause harm), consuming too much can cause unnecessary hospitalizations and psychological trauma. Knowing one’s own dose, therefore, is an important form of harm reduction. These quantitative test kits provide a significant contribution to safer use practices by showing users not only whether or not a certain substance is present, but also the concentration. This combination is unique among drug checking kits, especially those testing psilocybin.