Those are made by Raychem, they are the bees knees. If oyu want it to last forever, use those or the crimp versions. We use crimp versions on the race car, and they are bullet proof. The only problems with the solder ones you mention, is that the temp you gotta heat them to is very high. (to melt the solder).
These BABYs!!
http://www.rswww.com.hk/1/545269362-...MP-SPLICE.html

