As in Capillex or indirect? 2 different animals, born of the same mother.
1. Capillex (this is a brand, the correct name is direct/indirect or something stupid)
this film comes in different thicknesses, you stick it on a wet screen, it bonds with capillary action (better bond than #2 indirect see below) to the screen. When it dries (in the dark) you peel the backing and expose like a direct stencil.
Advantages - choose your thickness of stencil (for thick ink deposit apps) or where stencil thickness must be controlled (electronic circuits, UV, specialty printing)
gives an excellent edge to your printing (sharp fine detail)
Disadvantages - expensive, doesn't always work perfectly (probably operator error!) not water resistant
2. Indirect (5star, novastar, ulano hifigreen, there are a bunch)
This film is cut from a roll, exposed with a posi, then dipped in a mild peroxide bath, then washed out with warm water. You then stick it on the bottom of a screen, let it dry, and peel the backing.
Advantages - good edge detail, you can turn over a new screen and stencil in about 20 minutes. You can clean screens with this a bit easier, you don't need stencil remover, mainly because it flakes off so easy!
Disadvantages - look sideways at it and it will crack off the bottom of the screen, usually in the middle of a run or when you are peeling the backing - only good for solvent based, on higher mesh counts. Not good on shirts or fabrics on long runs.
It's hard to clean and reuse an undirect stencil because it is so delicate, in fact you will have trouble cleaning it at all.
Both are way more expensive per square foot than direct emulsion, and both don't have the toughness and cleanability of direct. I used indirect film for years, because that's what they used in the shops I worked and learned in. When I went to direct I never looked back. If you want a super sharp print, bottom coat your screens wet on dry to build the stencil up a bit, and buy a decent emulsion (dual cure or SBQ)