Every mirror should be equipped with a lanyard and should be able to be operated with one hand. Waterborne Signals Sea marker dye is a standard part of most aviation SEPs. Unfortunately, it doesn't last too long, dissipating in about 40 - 60 minutes in calm waters, much less in rougher waters. Now only Hoover, EAM and BFGoodrich include one. Winslow, Survival Products and Air Cruisers include the much smaller, really inadequate, Skyblazer sea dye package.
None is included in the RFD rafts.
This is far superior to sea dye. Just how important they are is questionable, but they could conceivably be of use if you ditch in well traveled waters or close to shore, in which case you want it to be as loud as possible. A whistle is included with every kit. Hoover fails to include a lanyard on theirs. Air Cruisers, Survival Products, Winslow, RFD include a basic pealess survival whistle.