Handsome wood post caps capture the design sophistication and attention to detail that exemplifies classic American architecture. 
A simple search on local and Internet wood deck suppliers easily come up with over 100 different styles of decorative post caps for wooden posts.
Most post caps are available in several of types of wood including Pressure Treated, Western Red Cedar, Mahogany, and Redwood. There are even colored glass and metal caps as well as caps that have low voltage or solar lighting
Post Caps dress up your outdoor project. They certainly look more finished than “clipping” the 4×4 post top with a saw. One of the best reasons to install a post cap, other than aesthetics, is that the cap shields the post tops from the elements. The cap eventually may need to be replaced but the post will not. Posts are way more costly to replace than caps.
Mahogany Post Cap
I’m a big fan of the Mahogany pyramid post cap. If maintained the Mahogany Post Cap will provide years of elegant protection to any post. They can be used on different size posts and work well on finishing your fence, lamp post, mailbox post, porch and deck railings. Available widths: 4-Inch, 5-inch and 6-Inch: mahogany.
Pyramid caps are made with a abetted block for better securing of the post cap skirt molding.
To install a Mahogany Post Cap follow this simple install method.
1. Remove the paper label on the inside of the cap.
2. Apply exterior grade construction adhesive to the post cap and side edges – don’t put too much that it will squeeze out.
3. Apply the cap.
4. Secure the cap with galvanized or stainless steel finish nails. If hand nailing – pre-drill first.
In the photo below I am using my Paslode T250A-F16 16 Gauge Angled Finish Air Nailer. I prefer this nailer because it is lightweight and compact, fitting into those tight spots. It consistently delivers well placed nailing in all types of wood species, even hard mahogany.
5. Consider pre-finishing the caps prior to installation. Make sure to finish the underside too.
