* Haoge LMR-SM140 Ring-type Tripod Mount * Used with SIGMA Contemporary 100-400mm F5-6.3 DG OS HSM (for Nikon F). * Arca-Swiss plate compatible. * The lens can be directly attached to a tripod using the 1/4 inch and 3/8 inch screw holes on the bottom. * The lens will slip if the tightening is loose, so it's best to tighten it with considerable force. I think it's easy to use. I've used it many times, and it worked without any problems. * The bottom will be removed for shipping due to packaging constraints. * Since it is not new, and it has been stored by an amateur, please consider purchasing with the understanding of this.