Re the insulation, you use the tool to push the wire down between the jaws of the IDC connector, and the jaws cut through the insulation and contact the wire. That's why it is important not to damage the connectors, and why there is a limit on how many wires to insert

.
My broadband basic info/help site - www.robertos.me.uk |
Domains,site and mail hosting - Tsohost.
Connection - Plusnet UnLim Fibre (FTTC). Sync ~ 58.7/14.6Mbps @ 600m. -
BQM
"Where talent is a dwarf, self-esteem is a giant." - Jean-Antoine Petit-Senn.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Allergy information: This post was manufactured in an environment where nuts are present. It may include traces of understatement, litotes and humour.