I have a couple of motorcycles that I ride regularly and one of them, a HD V-Rod, will drain the battery even with the key removed from the ignition. This is due to the multiple sensors that the bike relies on to monitor things long after you've stopped riding for the day. The coolant system is a good example as the radiator fan may need to kick in and stay on for sometime after a hot day's riding. Plus the alarm system and TSSM draws power even when the bike is off... and it does so all night!I went through several years of foolishly planning on riding only to find the bike's battery had drained and the familiar click-click-click sound of not enough power to engage the starter motor. I would then trickle charge the battery for a few hours and finally head out on my way. Of course, this meant I was going through batteries at a rate of about one every 16 months. At $100+ a pop it just didn't make sense to keep doing this and so I sprung for the dual Battery Tender from Deltran.The tender itself comes with two tails which are supremely easy to hook up directly to your battery and it also comes with two sets of crocodile clips which can connect to the tails so you can charge or jump your vehicle without having to remove seats or side panels to access the battery.The tender box itself is small and has sufficient LED status displays so you know if there's an issue with the set up (red=bad, amber=tendering, green=good to go kind of thing). Do note that a battery with less than 3 volts will not work with a battery tender - a tender is not a charger in the traditional sense, instead it monitors the battery's state and gives it a little juice if needed. If your battery is completely flat you will need to charge using a standard charging system before tendering it.I'm very happy with this tender - I bought it in 2008 and have yet to replace the V-Rod's battery. That's three years now - so the tender has paid for itself and will continue to do so for years to come. If you have a motorcycle, especially one used only during the fair weather days, then you should definitely pick up a battery tender and I recommend this dual one for functionality and price.