The PJB Untouchable Disc-Lock is a high security superior product. It has a compact 21mm double locking shackle which is tested to a six ton pull. Furthermore, it has a multi-disc / anti drill cylinder with dust cover. This disc lock is Classe SRA and FFMC recommended - French approved and can be used in conjunction with any length of the PJB Ex-Caliber 14mm and 16m security chains for home use.