OnGuard Mastiff Chain With X4 Padlock (6'/10mm) MASTIFF SERIES | Ultimate protection for high crime areas. With slightly smaller, squared links compared to the BEAST chains, the MASTIFF series offers bicycle owners and powersport enthusiasts ultimate security for use in high crime areas. Oversized, titanium-reinforced hexagonal links render hacksaws and bolt cutters virtually useless, while tight inside link dimensions make prying impossible. Available in a wide variety of chain lengths and link sizes to match your security needs. Hexagonal and square links present more hardened surfaces than round links making sawing and cutting virtually impossible.