These special solderless (crimp-on) terminals feature heat-shrink insulation for a weather-tight connection.
Simply crimp the barrel as you would any solderless insulated butt splice, then use a heat gun or high-wattage hair dryer to shrink the insulation. An adhesive lining melts as the tubing shrinks to positively seal out moisture. The adhesive also gives the insulation a firm grip on the wire, providing a strain relief and protecting against pull-out. The crimp barrel is seamless, so you don't need to worry about indexing a seam with your crimping tool.
Red insulation color quickly identifies the size as fitting 18 to 22 gauge wire. Sold individually.