A. This air filter is designed for GY6 scooters and all - terrain vehicles (ATVs), belonging to the air filter category. It has a reasonable design and various matching specifications to meet the needs of different users. B. In terms of connection, there are multiple options for connection threads, seal ring sizes, inner diameters, intake pipe diameters, and exhaust pipe diameters, including 35mm, 38mm, 42mm, 45mm, and 48mm, which can ensure a closer and more precise fit with various vehicle models. C. It comes in two types: straight - mouth and oblique - mouth, which can adapt to different installation environments and usage scenarios. The flexible design makes installation more convenient. D. Regarding its external dimensions, the diameter is 45mm, the width is 100mm, and the height is 120mm. The overall outer diameter × height is 12×10 cm. This size design can ensure the efficient filtration of the air filter without taking up too much space. E. As a motorcycle modification accessory, it features high flow, which can provide sufficient clean air for the engine, helping to improve the engine's performance and efficiency. It can make the vehicle's power output more stable, bringing a better riding experience. Whether for daily riding or driving on special terrains such as beaches, it can perform well. It is a good choice for improving the performance of GY6 scooters and all - terrain vehicles.