BTMS-50 is a cationic emulsifier.

Because it is positively charged, it is perfect for use in hair care products. It coats the hair strand reducing frizz while conditioning your hair. It is also a great emulsifier for lotions, creams, body butters, and moisturisers, as well as emulsified sugar and salt scrubs. It offers a powdery and less greasy feel to other emulsifiers.

What’s the difference between BTMS-25 and  BTMS-50?

BTMS-25 contains cetearyl alcohol which is waxier than than the cetyl alcohol in BTMS-50. It also only contains 25% of the active ingredient Behentrimonium methosulfate as opposed to the 50% in BTMS-50, which means you need to use double the amount BTMS-25 to get the same conditioning effect as the BTMS-50.