Quick Splices?

Its use that style all the time in telecom, just specific to telcom, I think they are 3M UB taps. Actually I rarely use them as a UR (3 way) is easier to install and we got cases of them. The blade doesnt cut the wire it just pushes the insulation aside and the wire itself nests in the groove. We only use solid core wire though, not the stranded you find in a car. Our amperage is milliamps but can get a shot of 90V AC through them @ 40 mA when ringing as well as up to 220V AC when they are installed as a T-1 or digital carrier, those will bite when touched with a knee in a puddle!