I collected several sizes and variations of these, years ago, because I knew they would be hard to come by later. Much more dependable than crimp types, and can be easily removed for troubleshooting/maintenance.
Though the line taps do puncture the supply line insulation, they are much less likely to cut the conductors than the Scotch types.
The Posilock uses a convex, cone-shaped, internal conductor that fans out the wire ends-much less resistance in the connection.
If you are not able to solder and heat-shrink a connection, this is your next best option.
Posilock also makes weathertight versions, as well. (Posted on 6/2/11)