Where would you normally use timber newel post caps ?
On top of a 90 x 90mm post on a staircase to dress it up.

What is it made out of ?
Plantation grown Meranti (aka Durian or Pacific Maple).

What are the important dimensions ?
Overall : 57mm Height x 140mm Width x 140mm Depth
On the bottom there is a 90 x 90mm rebate that allows the cap to fit over the post.

How should you finish it ?
If looking for a natural finish, then a clear lacquer will be fine; or you can use a stain to achieve your desired colour then use a clear lacquer to finish it off.
Speak to your local paint retailer for more info.