Ah yes the excellent MAUN pliers ,American I think ,when my mum was teaching,she had one of their rulers in black,and pressed into a W shape.Some parallel jaw pliers. I've been meaning to get some of these for ages.
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The two on the left have sprung arms. One has straight jaws, the other has jaws that taper to a point. The one on the right without the spring has serrated teeth and a little v-groove scored in it. I didn't realise when I ordered it that it lacked a spring, but c'est la vie.