I've just become the happy owner of the Vertax D15 for my Nikon D7100. I have to say I was a bit nervous at choosing this product after all it is one fifth the price of the Nikon battery pack. When I fitted it to my camera I was so pleased I had chosen it, I saved myself £200:00 without any detectable difference in quality. It fits my D7100 perfectly and feels robust and comfortable in my hand. Pixel the manufacturer has even thought about the rubber seal fitted to the camera to protect the connections at the bottom of the camera, they have included a place to keep it whilst the battery pack is fitted to the camera. There are two options for batteries either the Nikon EN-EL15 battery for the D7100 or six AA batteries. There are two easy to use trays supplied for both types of batteries. I've not used it attached to a tripod yet in outdoor work but the battery pack is so robust I am certain there will not be an issue using it on a tripod. The shutter release button is perfectly positioned to allow shots to be taken vertically, (portrait) The joystick works a treat when scrolling through camera menu. I have no reservations at recommending this product.Pixel Pro Vertax Battery Grip for Nikon D7100 Digital Camera as MB-D15