Coin-type tool with flanged hole to adjust the side wire without damaging the centre element and outer rim to measure the electrode gap. Metric 0.5 – 2.55mm, imperial 0.02 – 0.1″. Solid alloy steel. Coin-type tool with flanged hole to adjust the side wire without damaging the centre element and outer rim to measure the electrode gap. Metric 0.5 – 2.55mm, imperial 0.02 – 0.1″. Solid alloy steel.