Many personal players do not provide quite enough volume to blast over wind noise or past earplugs. There’s just too much ambient roar. The Boostaroo can help. Plug it into the ‘phones output jack of your radio/scanner/whatever, then connect your helmet or earplug speakers. Voila, it amps-up the sound by about a third. Input device volume adjustments remain functional, but everything tops at a greater volume. Clearly and cleanly, too. About a 12db volume gain in a typical ear bud speaker. Two AA batteries (not included) last about 20 hours. There are two jacks so a passenger can also listen along without complicated wiring. 40mw per channel.