Master Link Pliers

Modern derailleur chains reinstall on a master link more often than they reinstall on a pressed pin. Most 11- and 12-speed chains ship with one or two; SRAM flat-top AXS chains use a flat-top variant, KMC and Shimano publish their own quick-link patterns. Putting them in by hand works on a clean bench, but the snap into place is easier and more reliable with a tool designed for the job. The Master Link Pliers 1720/4DP do that in one squeeze, and they take a master link back out the same way.

The dual-function jaws are what separate this from an open-only or close-only plier. One pair of pliers handles installation and removal; you don't carry two tools, and you don't fight a closed master link with thin-nose pliers when you need to break a chain to clean it. The body is laser-cut steel, heat-treated for grip on the master-link plates, and the handle is double-dipped for hand comfort during repeated use.

Compatibility

The 1720/4DP works with most 6- through 13-speed derailleur chain master links, including the flat-top master links on SRAM AXS chains. The geometry is designed around the master-link plates that current chain manufacturers publish; chain widths within that speed range share enough plate geometry for one tool to cover them.

There are master links the 1720/4DP won't open. Proprietary or one-time-use links that are designed not to come back out (some 12-speed PowerLocks) will resist the plier, and the design intent of the chain is to replace rather than reuse them. For those, the right move is a new master link, not a harder squeeze on the tool. If you also need to break the chain at a non-master-link point (for cleaning, or to size a fresh chain), the Chain Breaking Pliers 1640/1DP handle that single-stroke; the 1720/4DP and the 1640/1DP cover the two halves of the chain-service workflow.

Specs

• Most 6-13 speed derailleur chain master links, including SRAM flat top
• 160 × 56 × 74 mm
• 74 g
• Dual-function jaws: opens and closes master links
• Laser cut and heat treated
• Material: premium flex plus carbon steel
• Surface finish: trivalent chrome plated to ISO 1456:2009
• Double-dipped handles
• Article number: 1720/4DP

Built in Zreče, Slovenia

Unior has been forging hand tools in Zreče since 1919, and is the official technical partner of multiple World Tour and downhill teams. The 1720/4DP is small enough to live in a workshop apron or a saddlebag, and substantial enough that you can feel the master link engage when it clicks home. The combination of laser-cut precision and chrome plating to ISO 1456:2009 is the workshop standard; the same finish that survives years of bench grease and brake fluid.

Pro tip from our mechanics

The plier itself is the simple part. Knowing which master link to use is the harder one. Reusing a 12-speed PowerLock is a common home-mechanic call that goes wrong; the link is engineered for a single install, the second cycle introduces play that the chain doesn't recover from. Our chain-replacement guide details which master links each manufacturer publishes as reusable, which are one-and-done, and the routing details that prevent a master link from coming out at the worst possible moment: When and how to replace your chain →