Either one will work in sealing around your windows so I'd not worry about what it is called, I have used both and seen little difference. I'm sure what is used in today's trailer manufacture is probably the least expensive one, not necessarily the best one.
As a friend of mine often says "I now Plead and Drink the Fifth" on this one!
Thats easy for you to say you have a roll of what you know to be the right stuff!
Hard to believe that actually buying and figuring out the right stuff is so difficult. I know I went to a fair bit of effort to get the roll I have now only to discover here that it may be questionable as to whether or not it really is the *real* right stuff.
The suggestion they are both usuable is probable not fair off providing what you have is in fact sticky & streaches out well - the question is more likely how long will it last 10/15 years? vs 20/25 years? either way I am willing to bet it will last longer than caulking
Trailer: Trillium 1300 Nor'Easter Egg '06 Ranger Supercab 3.0L auto
Try a decent marine supply store. The stuff we use on yachts is grey, about 1/2 to 3/4 inch wide, maybe 1/8" thick, stretches to eternity, isn't gummy to handle but sticks to anything dry and clean like crazy once the fasteners are tightened, and remains flexible and adhesive for a long, long time.
I've used everything clear of nuclear power trying to get old butyl tape to let go of the fiberglass, and have even been known - very occasionally, of course - to utter a mild oath or two when trying to convince it that it has really had its day after 35 years under a piece of deck gear subject to forces in the 1000's of pounds...if it doesn't leak there, it'll seal the Trill's windows just fine...
+1 what Ed says. The lateral creases on the inside of the roll. No sheen to the surface. That video from Donna tells the story on stretch potential in the real McCoy.
There are volatiles in both types I think. I keep what's left of my roll of butyl double bagged in Ziploc bags to try to make them stay in there. I leave the Camco stuff exposed to the air to see how long to rock hard. Doesn't seem fair to Brand X.
For the OP - be aware that there are two similar products sold side by side. The butyl tape is extremely sticky and will stretch into hair fine stands. The similar putty is less sticky and does not pull into strands without breaking. You want the butyl.
Yup Francesca I think we got that a while back. ;-) The basis of most of this thread and the main issue is that various companies (including some RV & Boat shops and body shops) are selling a product they call Butyl tape and it looks a lot like the Butyl tape, you have posted & what the OP posted the photos of but its really Butyl putty (which is a little less sticky). Trying to find an easy way to tell which is which so we all get the right *real* sticky stuff. Not as easy as it sounds! apparently. But I think the answer is to finger test it. If it doesn't *seriously* stick to your fingers it Butyl putty not tape.
This product I sell is used on a truck camper production line used everyday. The camper production company is Superior RV Manufacturing in Vancouver,Washington. I have used this product on a Scamp,Compact Jr, and a U-Haul. I would not sell a bad product to any fiberglass trailer owner or anyone else.