Here is my current inventory. The 6 HPs on the left were on Bob C's recent aluminum run. The aluminum HP next to that is one of the first HPs made in aluminum. Then I have 3 clear HPs made by Cal, very nice parts there. On the right the darker HPs are made by Don Jar, pretty brittle material so be very careful handling them.
I recently got these HPs and radar eye in clear resin from Cal. I can't say enough about how awesome these parts are! They are pretty solid. I think if one dropped one from 4 feet to the ground it won't suffer too much damage. Not that I plan on that but they are very well made IMO.
Here is each HP part side by side for comparison.
The old school HP is a little higher then the parts currently being run on and off.
I was surprised the end caps were interchangeable on these parts made by different people. They don't screw in all the way unless you use some grease and force but its pretty dang close.