STEPLESS CONTROLLER: Small 120mmx6 computer fans with speed controller,wide range of speed choice,you can easily adjust the speed from silent(1000rpm) to high speed(3000rpm) according to different applications. BIG AIRFLOW 93CFMX2: The speed controller 720mm fan with full speed 3000rpm around 93cfmx2 (while others are 2500rpm 85cfmx2) for those who need high power fans. LONG LASTING DUAL BALL: High speed 720mm brushless ventilation fans with dual ball bearing provide longer lifespan up to 6000 -100000 hours (over 6years). FLEXIBLE ARRANGEMENT: Each set fans with screws,fan connection brackets,metal guards,cable ties,you can easily assemble it for flexible length and width. WIDE APPLICATION: With stepless speed controller, the fans can be used for router,amplifier,cabinet,green house,fish tank,dog kennels,plant sheds ventilation and other diy cooling projects.