Using these HQProp T3.5X2.5X3 propellers is easy. First, make sure to choose the right shaft option that fits your device, either 2/1.5 or 2/2mm. Then, attach the CW and CCW propellers correctly according to your device's requirements. When using, avoid high - speed collisions to prevent damage to the polycarbonate material. For maintenance, regularly check the propellers for any signs of wear or cracks. If you find any issues, replace the propellers promptly. Keep them in a dry and cool place when not in use to prolong their lifespan.