These are positively indispensable imo. I've added to the kit with lots of additional accessories, and there's other kits here with more crap, probably like everyone else here. Each of the heads is outfitted with the parts to complete it with I think the exception of one that's a "spare" of the big heavy duty one for high amps use. I'll post the pics in a moment from my tablet.
The heads screw onto the flex-torch handle and are sealed by a silicone covering on both the heads and handle. The pic should show how it works. The tiny little heads for going down inside tubes and such are awesome. Also, the pencil style for pointing straight down into an item, they're wonderful for when that's the only option you've got. Even the heads with right angle or slight angle, you'd be surprised even with a flex head how often you want one or the other. Probably, it's like using a calculator and you forget how to add because you get spoiled never having to do that. These make it so you're rarely uncomfortable so you probably get out of practice at odd welding positions. I'm good with that.
I am not sure if it's ok to post links such as this, but here goes...
Head Kit https://store.cyberweld.com/wetigtokitak1.html
25' Torch https://store.cyberweld.com/wetigtowpmof.html
This did NOT come with a zipper cover for the torch hoses.
I stole the cover that came on the torch that came with the welder which was also 25'. I was gonna just buy a cover for $20 till I saw how proud Miller was and decided that torch on the shelf doesn't need one. 
