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Seatylock Mason U-Lock LARGE (Sold Secure Diamond)

  • £79.90
  • Free delivery

Seatylock Mason U-Lock 220mm (8.7 inch)
Seatylock Mason U-Lock 300mm (11.8 inch)

Mason, the world's lightest Sold Secure Diamond rated bike lock, now available in compact 140mm or 180mm triangulated shackle lengths, and long 220mm or 300mm pentagonal shackle lengths.

The compact 'mini-D' configuration is ideal for securing a single bike in theft prone areas. The high level of security is achieved by use of a unique triangulated 17mm thick shackle for the best strength to weight ratio. The Longer Mason locks adopt a complex 15.3mm thick patented pentagonal hardened steel shackle which is also the widest of its kind, ideal for securing multiple bikes.

Every Mason lock features a double deadbolt crossbar locking mechanism for protection against twist attacks and an anti-drilling key cylinder. Seatylock have ensured lasting durability by using rust free hardened steel and a rattle free dampened design.

Mason is ideal as a theft deterrent for longer duration security in city centres and other locations where stealing a bike may go completely unnoticed. Other suitable applications include additional home security used in conjunction with a ground anchor in the event of a garage break in, and higher value protection for e-bikes or motorbikes.

Don't be an easy target. Seatylock, for the bike you love!


  • Sold Secure Diamond Standard
  • Patented Triangular and Pentagonal shape shackles in four lengths
  • Double deadbolt and Anti-Drilling components in crossbar
  • Automatic cylinder shutter mechanism 
  • Bike frame protection with plastic coated sheath
  • Rattle Reduction Mechanism
  • Wide Clearance
  • Protected against the elements

PLEASE NOTE: Compatible frame mount is available as an optional extra via the following link: Seatylock Frame Mount

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