Master links are on 1/8" (and other ) chains ... 3 pieces . 1 with 2 pins, 1 with 2 holes and a spring clip.
Opening the spring clip one uses a screwdriver to pry it open .
Quick links are standard on some derailleur chains like KMC, Whipperman , their 2 pieces with a pin and a hole , are the same piece twice.
Most efficient way to open them is a Pliers made to use for that, to squeeze the 2 rollers the pins go thru.
Last edited by fietsbob; 11-24-15 at 03:29 PM.