FESTO stands for professional compressed air accessories from the industrial sector and has increasingly established itself in model building for various compressed air applications. In model building, pneumatic retractable landing gear is primarily used, which incorporates FESTO products. FESTO is always the first choice for compressed air accessories. For Festo hose connections suitable for an inner diameter of 3 mm, a hose with an inner diameter of 2.5 mm can also be used. AD stands for the outer diameter of the corresponding hose, and ID stands for the inner diameter of the corresponding hose. QH-QS-4.