2,6 & 8 ring terminals nylon insulated feature a silver brazed seam that will not open while crimping .  Groved barrel locks strands after crimpting after, crimping.  These terminals provide consistent performance in a variety of industrial, marine, military and aircraft applications.  Manufactured by 3M.  The color reflects wire size per awg code. Temperature range:  -40 - 221 degree F.   UL listed and CSA certified for 600v building wire and 1000v signs and lighting fixtures.