I've searched far and wide for a replacement, but it would appear that, as all of the lights of that form factor use the exact same battery (from the SL to the PRO) that Cygolite had a pack spec'd for them, and they're the only people that have 'em. My HotShot PRO 150 is closing in on it's 2nd birthday and still gets 10-12 hours on triple flash. I was hunting because my wife's HotShot 2W is getting a little long in the tooth, and it seems a shame to retire a perfectly functional light just because the battery is starting to tank. But a PRO is maybe $33, so when the time comes, I'll just pick up another.