The Exell A28PX 6v Alkaline Battery (L544BP V28PXL K28L PX28A A544) provides high-efficiency with long-lasting performance, and it is an ideal replacement battery for many applications. These applications range from vintage cameras, medical testing equipment, dog collars, and headlamps. It is also used in products from brands like PetSafe, Yashica, and Black Diamond. The older mercury batteries are no longer manufactured due to their high toxic levels. The Exell A28PX 6v Alkaline Battery (L544BP V28PXL K28L PX28A A544) is a popular replacement for the discontinued mercury batteries like PX28, 4MR44, V4034PX, 4H-C, 4NR44, and HM-4C.