What's New With Deck Railings | Professional Deck Builder . Nov 14, 2013 . You'll find railing posts and decorative post caps in a variety of materials and colors, some with integral low-voltage lighting. If you still want to install 4x4 posts, you can buy finished post sleeves to slip over them. To reduce on-site work, many manufacturers offer pre-cut balusters and preassembled rail..