Double Ended Box Spanner Non-Sparking Secure Tools's Non-Sparking Double ended Box Spanner is mainly made of steel tubes, the double sided Non-Sparking box spanner is typically used for removing spark plugs. They normally feature a six-sided ring-type head that fits the nut that has been pressed out of the steel tube during the manufacturing process. They are turned using a T-bar passed through the two holes in the middle.