Our latest disc brake rotor lock rings can be fitted and removed using two different tools. You can decide to use one or the other, or maybe have both available as a backup.
The outer circumference of the lock ring engages with a standard 16-notch external BB tool. With our older lock rings, this interface was the only available option. These tools are widely available from all bicycle tool manufacturers. A good quality example would be the Park Tools BBT-69.4 Bottom Bracket Tool. The BBT-69.4 mounts onto a 3/8” ratchet so you can use a torque wrench to make sure you have achieved the recommended torque of 40nm. Many other variations are available, including those with their own handles, although of course, this makes it impossible to verify torque so we cannot wholeheartedly recommend these.
On our latest lock rings only, the inner circumference engages with a Shimano TL-LR11 tool. This tool has spanner flats, but ideally should be used with a ratchet/torque wrench. Whilst this isn’t the most common tool (it differs from a visually similar regular cassette lock ring tool to give increased clearance), it is sometimes useful to have another option should the outer circumference become damaged.