This Exponent is the Thumbstud version with a Zirconium thumbstud. This knife opens smoothly and locks up solid and early on bearings.The lock disengages and the blade falls shut smoothly. Or US Address sales only. This item is in the category "Collectibles\Knives, Swords & Blades\Collectible Folding Knives\Modern Folding Knives\Custom & Handmade". The seller is "knifeguru82" and is located in this country: US. This item can be shipped to United States.