Size:303# Specification Package: 10Pcs 303# Carbon Brushes for Grinder Material: Carbon, Metal Main Color: Grey and Gold Tone Carbon Brushes Size: 5x11x16mm /0.2x0.43x0.63inch (L*W*H) Total Length: approx. 37mm / 1.46inch (with spring) If the carbon brush is used and worn, you can measure its length and width to choose your right carbon brushes. 1. Manufacturers recommend replacement after 60 hrs. 2. Always be prepared and keep 30pcs in stock. In case for need. 3. This Type of Carbon Brushes is Self-stop Carbon brushes. 1. Self-stop carbon brush meaning: after the end of production, after filming to confirm that the spring and safety sub assembly is correct. When the carbon brushes grinding to the safety sub position, tool stops working automatically. Without Self-stop does not achieve this effect. 2. Application: 303# 5x11x16mm Carbon Brushes Fit for 4100NH, Z1E-FF-110 stone cutting machine, Q1U-FF02-160 mixer, 5740R, M1Y-FF-185 electric circular saw. The above machine model, we deleted their brand name. Detailed machine please contact us. If replaced the new carbon brush, the carbon brush have been finished or worn out half. It means your rotor was on fire. Please replace your rotor, if you don't change the rotor, it is useless to change more carbon brushes. Note: It will burning the carbon brush when the rotor is burning. Sipery Service 1. Customer service: We guarantee your 100% satisfaction! If within 30 days you are not satisfied with our products, please feel free to contact us. We will refund or replace your order to provide a best solution! 2. Kindly Note: Please allow 1-2cm errors due to manual measurement, thank you for your understanding!