THC ( Delta-9 THC) is most famous for its psychoactive properties and the "high" feeling users describe. Traditionally Delta 9 is known to be found only in cannabis products, but now after years of research and development, manufacturers have figured out how to extract Delta 9 from the hemp plant.
How is this legal? According to the 2018 Federal Farm Bill, any hemp derived product that contains less than .3% or 3mg per gram by dry weight of Delta 9 THC is federally legal. Some products are up to 10g in dry weight and therefore can contain upwards of 25-30 mg per dose.