Aiwo L-TC contains 250mg L-Theanine & Caffeine 100mg. It is a popular nootropic stack. L -Theanine is an amino acid naturally found in green tea. L -Theanine significantly increases activity in the alpha frequency band, which indicates that it relaxes the mind without inducing drowsiness or negative side effects associated with other calming agents. Caffeine acts as a central nervous system stimulant.