Firehose Key Pouch
Use of a single robust ring minimises the chances of any individual key accidentally coming off.
Less manipulation is required to deploy the keys from the pouch, as they all just flop out at once. Not even a metallic snap to weaken or wear out.
The line that holds the key ring to the pouch should be changed occasionally, as it can abrade and break.
I've used this for several years now, and am satisfied with the design.