21 Pc Cobalt M42 Drill Bit Set 1/16" to 1/2" by 32nds DRILL HOG USA

what's the difference between these and the Molybdenum M7?

Where is the contact info to replac bits through the warranty?

Dose this set have a 1/2 , 9/64 and 23/64

If drill hog is made in the usa why can’t i find their address or phone number???!!!