This is a side deck plate for mounting a Bimini Top. This fitting has the 1/4" 20 bolt. It is stainless steel. If you have any questions let me know. It will be sold as a pair. I will combine the shipping for multiple items. Please check our store for other boating parts and supplies. The base size is 7/8" x 2" .The mounting holes are for a size #10 screw.