These propeller guards are perfect for micro quad enthusiasts. Use them to safeguard your 3' micro quad's propellers. They have an inner diameter of 79mm, an outer diameter of 90mm, a guard thickness of 2.5mm, an installing hole of 9 - 12mm for the motor, and are suitable for 3' maximum propellers. Made of Polypropylene (PP), they weigh 7.5g per piece. Comes with 4 HGLRC 3' Prop Guards.