The RRS-BT-Combo is the pairing of the RRS-BT (Bino Tower) with the RRS-BT-M1 (1/4X20tpi Mount). No other components discussed here are included. This is the most popular and commonly purchased Tower/Mount combo we sell.  Most binoculars manufactured in the Pacific Rim countries (Japan, Philippines, China)  have standardized on the front-hinge 1/4X20tpi female thread for the attaching binos to tripods. The RRS-BT is designed to attach to any tripod via it's 1/4x20tpi female thread located on the bottom center of the RRS-BT. It bottom is also beveled to quickly slide into the RRS-Shoe, or the RRS-KDC-NanoPanhead.  The RRS-BT is designed to attach to the RRS-OBAs, and lock in place with a 2X56tpi cap screw. The top loader design with the cam lock is simple fast and accommodates large object binos (56mm) with ease. Weighting in at an amazing .7 of an ounce, it is dovetails nicely with the KDC design goals of nano-weight and compactness.