D cell battery holders for physical science experiment or other use, sufficient quantity for you to use. Made of plastic and metal, this d battery holder parallel is durable and can be applied for a long time. These battery holders can be connected in a series to add voltage or in parallel to add current; With spring clip design, you can easily put the battery in it; Both ends of the box have positive and negative labels. Holders can be quickly and easily snapped together to form either parallel or series connections; They can be applied individually or configured in parallel or series via the interlocking tabs located on the top and sides.