If you're unable to find BTMS then you may experiment with using behentrimonium chloride or stearamidopropyl dimethylamine in its place. However, it's important to bear in mind that neither of these have been tested in our formulations so we cannot guarantee results. Additionally, because behentrimonium chloride can cause cationic buildup when used too frequently or in high concentrations, it's best to start with a slightly lower amount and gradual increase it if your hair tolerates it well.