Sorry for the low quality on this one, but i'm not blessed to have a 3.1 megapixel camera just yet. The pieces from left to right are...

Lifter Housing
Lifter Spring
Lifter Insert (contains the drain back valve)
Lifter Swivel-Tip

The spring goes into the housing and the insert sits on top of the spring. Where the spring and the insert meet, there is a tiny cap that has an even smaller spring and ball-bearing in it. That tiny tiny spring goes bad and causes the drain-back valve to stop functioning properly, making the lifters 'tick' or 'clack'. the swivel tip sits on the lifter insert and provides the contact for the valve stem.