Angle Grinder Resistance

Grinders are the tool of choice now, which is what a shackle has to survive.

Hardened Shackle Material

Bolt cutters and hacksaws both fail against the right hardened material.

Carry Weight on the Bike

A lock too heavy to bring is a lock left at home on the day it was needed.

Wraps Around Fixed Objects

Racks, poles, and railings vary, so shape decides what you can lock to.

Alarm or Tracking Alert

A noise or a phone alert interrupts a theft that a lock alone would only slow.