Concealed hardware for attaching both ends of a rail between 2 posts. Comes with 2 pair of stainless steel springs. 1 pair is right hand and the other pair is left hand. Can be used inside or outside. Tools needed to install and not included are a 1" wood drill bit and a No. 3 Phillips bit or screwdriver. Epoxy glue can be used, but is not necessary and is sold separately.