Rescue Streamer
The issue with most day-time signaling devices is the fact that they only last a short period of time.
A smoke device may be very useful if hep is nearby, but most hand-held marine smoke devices which are small enough to be carried by divers are not producing dense smoke for long. In windy conditions, the signaling effect might quickly wear off. Traveling with a few of them on commercial airplanes... don't even go there. A signaling mirror is useful and compact, but requires active signaling on your part - not ideal if you've already been drifting for half a day and are simply too exhausted to randomly scan the horizon with it.
One device that is again fantastically simple, but certainly effective, is a "Rescue Streamer". Basically a compact roll of plastic, which clips on to your D-ring or BCD and is held afloat and stretched by small plastic rods.
Available for around $30-45 USD from www.rescuestreamer.com or from Amazon.com: Survivor Rescue Streamer Distress Signal (In Mesh Carry Bag)
Available in a cordura holster that fits onto a 50mm webbing - always attached, lightweight, you never dive without it again.
Small and easy to take along:
Instructions for use are printed on it, but how hard can it be?
International distress markings at the end - possibly not very important - the main thing is that they can spot you from the air much easier if you are "a long orange mark against blue water" as opposed to "a little black dot in the ocean".
We really like it, and several of our dive buddies have already bought one after seeing ours. It is incredibly simple, and your first thought might very well be: "I'll just get a roll of construction site tape", but of course it won't float nor stay wide enough to look "different". Our only addition on how to improve this could be to have some sections of SOLAS reflective tape on the roll, similar to the dive signs we use on our SMBs.
