The Prova railing system from DOLLE offers interior and exterior railing systems that are component-based, easy to install, and beautifully designed. The Prova railing system offers several different configurations that provide a sleek, contemporary, custom look at DIY pricing. Prova railings are perfect for any home - creating dramatic sightlines outside, and making small spaces seem larger inside. Prova PA22b lag screws are constructed of zinc plated galvanized steel. PA22b lag screws are used to secure Prova aluminum top and side mount posts into a wood or composite backing. Requires a 5/16" pilot hole for installation. Prova top mount posts require 4 screws per post, side mount posts require 2 screws per post. No special skills required - Prova is designed for easy assembly with basic hand tools. Prova railings by DOLLE are the perfect railing system for today's modern, open floor plans inside while also providing beautiful, unobstructed sightlines outside!.