Thin mil parachutes are made of 1.1 oz. zero porosity ripstop nylon. You know, that filmy feeling stuff. Consequently, the chutes are extremely light for their size.
The thin mil parachute is the one to get if you have to get a reasonable-sized chute into an unreasonably small body tube.
These chutes are more efficient than a Estes poly chute (even before it gets a bunch of holes in it or gets half melted) so you can go with a smaller size. We will put a decent rate calculator in the Hints and Tips section shortly.
If you want a spill hole, please make a hole with sharp scissors and "polish" the cut with a flame CAREFULLY. Spill holes make the descent faster and prevents a lot of swaying.