[NOTE: Fits Tank Rim up to:12mm thickness (adjustable) /Suggestions:2 fan fit for 40cm fish tank /Two-speed wind controlaccording to the indoor temperaturereduce water temperature and drop up to 2 ~ 3℃ Adjustable jaws can clamp the the cylinder wall that the thickness within 1.2cm，meet the daily use of fish tanks Great cooling fans 12V safe voltagewith high security standards and ensure the safety of the fan Angle adjustable:Adjustable width of fan and bracket up to 100°practical and easy to install and move Safety Packing With Wonderful After Sale Service: We provide with 90 days return and refund service and all the emails will be replied within 24 hour. We provide lifetime technique support if you have any question please feel free to contact us.]