Take a look at the Dynamite/losi shocks. They are the ones I am going to get, eventually. They don't have a cap, so you can't blow it off. You fill them from the bottom. They are threaded for easy adjustment, and come in a variety of colors. I am defintiely going to get a set of these, when I am done buying other hop ups .....

Here's a link the the Dynamite website http://www.dynamiterc.com/Products/D...uctID=DYN7636S

You can get them cheaper than this, just got to find other sites that sell them. I can't remember any of them off the top of my head....