Butanox L-50
Butanox L-50, Methyl ethyl ketone peroxide, solution in dimethyl phthalate, CAS 1338-23-4, Organic peroxide, Butanox® L-50 is an ideal catalyst used for curing promoted unsaturated polyester resins at room temperature.
https://www.nouryon.com/product/butanox-l-50-methyl-ethyl-ketone-peroxide-solution-in-dimethyl-phthalate-cas-1338-23-4/