You can see Starscream's in this thread:
http://www.rc-monster.com/forum/show...=&threadid=441
Basically,the 2 end caps compress the cells together using some threaded rod and some spoke nipples.
They sell silver paste seperately which you brush on the cells to lower the resistance further.
Their race packs use the same end caps as the standard SPT kits/packs exept they use different contacts to make the pack slightly shorter for fitting in touring cars and such like.Same end cap though.I got the standard,i think its better unless you need it to be a few mm shorter.