"Bronco" is kind of a code name for a type of triplex or quadruplex we use out in the oilfields for 480V overhead linework. CME is a UL listed mfr., with most, if not all it's products made south of the border (Their romex says "Proudly made in North America
)
here's a link
http://www.cmewire.com/products/ix600sdc.asp Funny though... they list the 336.4 as "NannyNose"
BTW... I dont think this is made for in the home use