Abstract: A one piece, injection molded, post cap for covering the upper end of wooden posts, poles, and pilings. The cap is made in discrete, sizes and shapes and having internal structure to allow installation of each size over a range of diameters or dimensions of posts. The caps are decorative and the internal structure assures the caps remain in a desired vertical uniform position relative to the post so a row of posts has an attractive appearance. The internal structure comprises tiered rows of collars or fingers which are expanded or forced upward at their internal edge or ends so as to engage the post and resist removal of the cap. The caps may be provided in common shapes and sizes so as to fit over posts having cross sections which are round, square, oval, or oblong.