Terahertz High Purity 15N Polished Finish There are some areas that are slanted. Because of the high purity, you can also make terahertz water with a massage stick. Please refer to the size in the photos. For those purchasing multiple items, please understand that the size and weight will vary for each item due to the terahertz 15N polishing process. While you don't need to be overly concerned about purity for Gua Sha plates and massage sticks, if you prefer 15N, please purchase this. This is a set price, so only combined shipping discounts are available.