Features: Make of carbon steel materials, with precise craftsmanships, smooth, no burrs, corrosion and rusts resistance, not easily to break / deforms, and Enduring. Mainly used to fix equipment that is often disassembled, fasteners in the mechanical industry, installed in mating key way, suitable for pulleys and drive shafts applications, and transmit torques between shafts and hubs / bushings. Easily to Store: All feather key is store in a clear and sturdys storage box with compartments. All Key Stock is all make by highly precisions process center. Suitable for pulleys and drive shafts applications, and they is suitable for hubs adjustment. Easily to carry, simple operate, strong function, highly accuracy, good repeatability! Specifications: Materials: Carbon Steel Size: As Show In The Picture Package Includes: 10Pcs 3x3x8mm 10Pcs 3x3x10mm 10Pcs 3x3x12mm 10Pcs 3x3x16mm 10Pcs 4x4x10mm 10Pcs 4x4x12mm 10Pcs 4x4x16mm 10Pcs 4x4x20mm 10Pcs 5x5x12mm 10Pcs 5x5x16mm 10Pcs 5x5x20mm 10Pcs 5x5x25mm 5Pcs 6x6x16mm 5Pcs 6x6x20mm 5Pcs 6x6x25mm 5Pcs 6x6x30mm note: Please allow 1-2cm errors due to manual measurement, make surely that you not mind before order. Due to difference between different monitors, the picture may not reflect the actual color.