Using these Bernard Centerfire Contact Tips is easy. First, make sure your Bernard MIG Gun is turned off and cooled down. Remove the old tip if there is one. Since these are drop - in, threadless tips, you can simply insert the new tip into the gun without using any tools. When choosing a tip, pick the appropriate size based on the wire you're using. For example, if your wire is.023' (.6 mm), choose the T - 023 tip. As for maintenance, keep the tips clean from spatter. After each use, check the tip for any signs of wear or damage. If you notice poor electrical conductivity or gas flow issues, it might be time to replace the tip. Store the tips in a dry place to prevent rusting. And always follow the safety guidelines of your MIG gun when using these tips.