Amazon.com: Eske Kouri Gobricks GDS-798 Brick 1X2 W. GROOVE-1x2 Brick with Vertical Groove Compatible with Lego 4216 All Major Brick Brands,Building Blocks ,Technical Parts ,Assembles (106 Orange(021),30 PCS) : Toys & Games
LEGO 4216 Brick, Modified 1 x 2 with Groove - WHITE (10pcs) | eBay
LEGO 4216 Basic Building Set, 3+ Instructions, Basic