they are actually a copy of a ADA kit
its also called a 3d kit on the ada webpage here is the link
ADA Racing 44mm Pocket Bike w/Boost Port Head Kit
they run the 10mm crank pin they tend to rev a little harder with the smaller pin & a 32 mm stroke = 48.7cc
rather than the 12 mm pin & 33 mm stroke that makes them 50.177cc
ADA price is $109 for the headkit alone plus shipping cost from USA so the kits from hyper pocket parts are very good value
