Precision machined and meticulously engraved with our industrial CNC mills, the Milspin slide back plates (butt plates) compatible with Glock are a premium upgrade. As with all of our products, we only use CNC vertical mills to engrave our finished products. CNC milled engravings take special care, skill, and time to produce but the final product is an elegant, three-dimensional engraving unmatched in both quality and durability and sure to last a lifetime. Material: Brass with a Green highly durable heat cured coating. EASY INSTALLATION. 100% No Questions Asked Return Policy on All Products. Milspin slide back plates (butt plates) compatible with Glock are made from high-quality materials and deep engraved with cnc mills making these back plates guaranteed to last a lifetime.