4x4 Post Base Support Flange Pro Version Handrail Support (actual size 3.5"x3.5") Trimming Posts Precisely and Properly Installing Screws Is Required Imported New Stylish Contoured Base  Trimming Posts Precisely and Properly Installing Screws Is Required Perfect for deck supports, porch railing, hand rails and post holders. POST MUST BE TRIMMED TO FIT Fits a nominal standard 4"x 4" post (actual 3.5"x 3.5").  Sanding / Trimming IS REQUIRED depending on post type and little size error.  Be sure the end cuts of posts are square and mounting surface is even. Maximum Post Height 36" Made from paintable durable High-Strength Nylon + Anti-UV + FRP (Fiber Reinforced Plastic). NO fading, aging, and weakening from sun exposure.  UV-resistant which meets or exceeds common Construction Codes. Use common sense with this and all decking products. Pro Version.  Stainless Steel 304 screws are included: 8 short screws (installed horizontally) to post. 12 long screws (vertically) to deck floor board. Thicker & higher post base bottom for better structural strength on decks. Contemporary style. Designed for Stylish decks. Fast & easy post installation in minutes. Mounts with #8 Deck Screws on Bottom Flange and #6 Deck Screws on top. *Screws included. For Concrete use: Tapcon 3/16 in. x 1-3/4 in. Philips Climaseal Steel Flat-Head Concrete Anchors. Thick high post base bottom for better structural strength.