The Master Lock No. S3924 Blind Flange Lockout device is a physical, best practice solution for pipeline maintenance. The adjustable cup allows for a secure fit that conceals and locks out access to nuts holding a blind in place. Workers can perform maintenance with confidence that the blind they placed on a pipeline will not be removed until all workers have removed their padlocks. 4 locking holes allow for multiple workers to lockout device at one time.