The type I use is Dow Corning RTV 3140. It is available in several sizes but I have found the 3 ounce tube to be the handiest. Infact I keep a tube in a small repair kit I made up as it is useful for many things.
Right out of the tube it can be used to seal or patch small holes in tent sides or floors. A small drop at the end of a tear in a tent can prevent it from spreading until a proper repair can be made.
It can also be used as a glue on some materials when straps, etc. break while on the trail. It can also be used to repair utensil handles etc .
Thinned out it can be used as a seam sealer or as a waterproof coating for stuff sacks and packs.
I have also used it as a coating on the polyurethane floor of a small 10 year old tent I have which was starting to flake off.
As I mentioned in my previous post, it doesn't give off acetic acid as it cures which could damage some fabrics.
For specific information here is a link to Dow Corning's page about it which has a downloadable material safety data sheet on it also:
http://www.dowcorning.com/applications/ ... DCCSF=21EN