Using this chalk box is a breeze. First, open the large refill port to add chalk or replace the felt if needed. Then, pull out the snap line and stretch it to the desired length. Make sure to hold the line firmly and snap it down to create a bold 0.07 - inch (1.8 - mm) line. When you're done, use the double - speed winding mechanism to quickly reel the line back in. As for maintenance, keep the chalk box clean and dry. Avoid dropping it or subjecting it to rough handling, as the heavy - duty aluminum case, while durable, can still be damaged. Check the felt regularly and replace it when it shows signs of wear. Also, make sure to refill the chalk when it runs low to keep getting those bold lines.