The painful shriek of these things will remind you not to ride off with them still still attached (it’ll train you faster than Pavlov’s dog). Disc locks add easy-to-carry affordable security, so they are popular, which is why they are so many available. These patented locks combine the strength and convenience of a traditional hardened body disc-lock with a piercing 110db motion activated siren. Which is much better. If anyone tries to move your bike, it screams loud enough to scare them and will draw the attention of those farther away. Certified by a number of rigorous European testing agencies. The ‘push down’ locking system auto-arms the motion and shock sensor. A better disk lock. The smaller XR 1 has a 6mm pin, 3.2""×2.3""×1.3"" and the larger XE 15 has a 14mm pin, 4""×2.5""×1.375"". Sale: Slight wear, missing 1 key.