Using the 90° Manual Stealth Seamer is easy. First, place it where you want to create a perpendicular seam. The non - marking vacuum cups will hold the pieces firmly in place. You can use the knurled rollers to pull the pieces together and the fine - tune levelers to adjust the angle until it's just right. Keep an eye on the easy - to - read indicators to make sure the vacuum pressure is good. If the pressure drops a bit, you can re - pump the cups without losing the remaining pressure. When using it, don't try it on porous materials or heavy waterfall pieces as it's not suitable for those. After use, clean the vacuum cups gently to keep them in good condition. If you're not using it for a while, store it in a dry place to prevent damage.