We left batteries in the battery holder that came with our Snap Circuit Jr. set, and they corroded. I was pleased to see that Robotshop had the individual part, since that's all I needed, and the price was right. I also like that fact that Robotshop offers the alternative shipping to lower the cost of shipping. It took a while to arrive, but I was in no hurry to get it. The product is exactly like the one that came in the original set, and it works well. I would recommend removing the batteries from the batter holder when storing the set, so the batteries don't corrode and ruin the holder.