I am always dubious of any connectors from HF, but I can definitely vouch
for the quality of the 3M connectors if used properly.  I have used hundreds
of them in my wiring kits over the years.

The best heat shrink connectors I have found are Perma-Seal brand.  They
have better quality shrink tubing and adhesive than any other brand I have
tried.

There are a few tools that work really well for shrinking the connectors and
activating the adhesive.  The first and easiest to find is a standard aim
and flame style lighter.  One step up from that would be the flexible neck
butane lighter from Bernzomatic
http://www.amazon.com/Bernzomatic-019585-Flexible-Stem-Lighter/dp/B000M3THFE
/ref=sr_1_1?ie=UTF8&qid=1381179030&sr=8-1&keywords=bernzomatic+flexible+ligh
ter.  I usually get about 10-15 refills before one of these wears out.

If you plan to keep using this type of connector for your electrical
projects, the ECG HG-300D mini heat gun works great, has no open flame and
won't melt anything near where you are working
http://www.amazon.com/ECG-HG-300D-Mini-Heat-Gun/dp/B003N3G4WY/ref=sr_1_1?ie=
UTF8&qid=1381179169&sr=8-1&keywords=mini+heat+gun.

Hope that helps,
Jay Brown
'85 Zetec Westfalia
https://sites.google.com/site/vanagonheadlightrelays/