No teeth, no spring, box joint.The edge is even slightly beveled so they won't cut into the rings.Made in Germany. Max Recommended Wire Thickness (*See Notes Above): Stainless and Titanium (SS/TI): 16gCopper (CU): 12gBronze and Brass (BZ/BJR): 16gAluminum (anodized AA and bright AB): 12g Minimum Recommended Size (*See Notes Above): 20g