This corner shower shelf is handcrafted from durable Limestone Quartz. The color is similar to tan limestone. It was made in our fabrication shop, has a polished eased edge & is 3/8 thick. The measurements (7,8,9,10 or 12) are from the front of the shelf to the point on the back. The 8 is the most popular. The under polish option is there if you would like to have the polished look on the bottom of the shelf. For example, your shelf is above eye level & you would prefer it look the same as the shelf beneath it. This Quartz shelf is a combination of natural quartz & other raw materials that are extraordinarily hard & resilient. It is stain resistant, scratch resistant & antimicrobial. It is easy to clean with a nonabrasive cleaner.. The shelves are to be set with tile mortar on top of a row of tile & the next row of tile cut around the shelf locking it in. If you are wanting to set this shelf on the surface of an existing shower check out our surface mounting bracket kit. This shelf also makes a great accent for any corner of your home. Perfect for showing off family photos or your favorite curios. Simply install with our bracket kit. Please refer to our website quickcornercaddy.com for both pictorial & video instructions on correct installation. Insurance is included in the shipping & handling of this item. If your shelf arrives broken we will ship out a new one at our expense. We will just need you to e-mail us a picture of he broken shelf. Limestone Quartz Stone Shower Caddy