I bought 4 pairs of these batteries and had initial concerns, but because they're quite expensive. They arrived then and I have loaded the Ansmann Powerline 5 Zero Watt, to slip in my boom box. I had gone from 5-6 hours. But what came next was enormous: I have more than 3 days to get those things yet. For low volume and louder.
Also the shipment via Mobile Energy was great. Super packed and quickly. 5 Stars!