These silicone fans for fasteners are very easy to use: just enter the fastener in the hole and shoot a little bit it until clipping. They perfectly fulfill their role as vibration damper while setting optimum manner and that the fan is on silent-blocks. After, no noise except that of the airflow. Perfect !! A highly recommended over direct mounting screws with noise generator due to vibration of ventilos Quickly delivered by box of 4 elements in ripstop shell (ordered on Monday and Thursday received in mailbox). Without concern !!