Amazon.com: Gobricks GDS-632 Special 1x4 with Masonry Brick Profile Compatible with Lego 15533 All Major Brick Brands Toys Building Blocks Technical Parts Assembles DIY (500 PCS,199 Dark Bluish Gray(072)) : Toys & Games
Brick, Modified 1 x 4 with Masonry Profile : Part 15533 | BrickLink
LEGO part 15533 - Lavender Brick, Modified 1 x 4 with Masonry Profile (Brick Profile) at BrickScout