Botox units measure biological activity, not volume; brands differ in potency

https://www.google.com/maps/d/u/0/embed?mid=1rMpxOUSGdciBIp4L_0tDg5QcsZinj6Y&ehbc=2E312F&noprof=1

Botox units measure biological activity, not volume; brands differ in potency, so dosing is not interchangeable unit-for-unit across products.