This is a bolt seals ,It is high security seals complied with ISO17712:2013.The diameter of male and female is more than 18mm. after locking ,The lock pin is fastened into the lock housing. The pin can not be twisted because it is metal and plastic antispin structure. 

Features 

Laser printed (Increased security) High impact plastic cover on locking chamber; plastic coating on rod; both clearly indicate tampering. 

Locking insert spins freely to confirm seal integrity. Metal locking end encased in a consecutively numbered body. Bolt shank and locking case are plastic coated and identically numbered. 

Removed with bolt cutters. 

ISO 17712: 2013 compliant bolt seal 

Brightly coloured for high visibility 

Serial numbers lasered onto body and bolt for higher protection 

Plastic coating protects bolt and body from corrosion