ProWood 4 in. x 4 in. Gothic Wood Post Cap Finial (6-Pack) 189296 - The Home Depot
Wood Finials, 3/4 Inch Tall with 1/4 Inch Hole, Unfinished Wood Finials for 1/4 Inch Dowel Rods, Wood Dowel Caps for Crafts and DIY, Pack of 100 by Woodpeckers - Walmart.com
Staircase Finial Newel Post Cap FN-0103 - JMP Wood