The Varavon Base Plate for Nikon D3100 attaches the Pro Finder viewfinder loupe to your DSLR camera. This base plate is made of solid aluminum and is about 1" (25mm) thick. A red thumb dial connected to a 1/4-20 mount makes it easy to attach or detach the plate from the bottom of the camera. A locking pin on the plate prevents it from pivoting once connected. On the side of the plate is a red locking thumb screw for securing the Pro Finder once it's connected to the base plate. A 1/4-20 mount on the bottom of the plate enables camera mounting to a tripod or stabilizer.