This is a battery holder for the Pentax 645. ☆Please double-check your camera, as some people mistakenly purchase this thinking it's for the 645N. (The 645N/NII version is also listed.) (Images 1 and 2 show the holder installed. The actual product is shown in images 3, 4, and 5.) A video is available on YouTube by "Hitori Photo" titled "There's a Substitute Battery Holder for the PENTAX 645!" This was made for those who need a replacement for a battery holder that has leaked, or for those who find it difficult to carry many spare AA batteries. This is not a genuine product, so the holder does not lock. It is secured by the friction of the felt and the force of the spring, so it may come loose if excessive force is applied. (We have sold several, but there have been no reported issues of it coming loose.) One 006P battery is included.