eModernDecor Over Mount Installation 16 in. x 28 in. ABS Single Shelf Bathroom Recessed Shower Niche for Shampoo, Toiletry Storage SHC-R-1628 - The Home Depot
AKDY 8-in x 36-in Matte Black Stainless Rectangular Shower Niche in the Shower Shelves & Accessories department at Lowes.com
Neodrain No Tile Shower Niche, Stainless Steel Wall Niche 13.1"X 25.1"(Inner Size 12"X24"), Two-Tier Bathroom Shelf, NO Tile Needed Recessed Niche Shower for Bathroom Storage - Walmart.com