This is a Pentax release remote control. I have confirmed that it works without issue on a K100D. Please provide your own CR1620 battery. Instant purchase is OK. It will be shipped via Yu-Packet Post Mini. Thank you. The following is an excerpt from the instruction manual: Remote Control F You can wirelessly operate the shutter release of a Pentax digital SLR from the front of the camera. The shutter will release 3 seconds after pressing the shutter button on the remote control. (Immediate release is also possible depending on the camera settings.) The K-5, K-7, K20D, and K10D can also be used from the back. In addition, the K-5, K-7, and K20D can also use the remote control for continuous shooting.