6 Piece Koken 3/8" Drive Wobble/Fix Extension Set (PK3763/6)

Engagement feature is positive and robust, socket and detent are well formed. Knurling for hand starting fasteners is excellent. Haven’t put them to an ultimate torque or abuse test, but I hope and expect that they will adhere to Koken’s high metallurgical standards. While certainly less expensive than tool truck brands, they are still pricey.