KD sockets, wrenches, and other hand tools stopped being made more than a few years ago to allow for Gearwrench's expansion. The KD auto specialty tools is still active. Where are you buying them? The reason I ask is that most online vendors use a KD part number for Gearwrench tools. Gearwrench tools although being great tools, are mostly made in China.
Old stock KD sockets are basically the same as the off the shelf Danaher made Craftsman, Allen, 2nd generation Kobalt, etc.
Keep in mind that the Apex tool group is the Chinafication of formerly US tool brands.