BrickLink - Part 3003f1 : LEGO Brick 2 x 2 Transparent with Frosted Horizontal Line and Two Vertical Lines Each Side [Brick] - BrickLink Reference Catalog
Creative Transparent Bricks 11013 | Classic | Buy online at the Official LEGO® Shop US
A Clear Path Forward for Transparent LEGO Bricks - BrickNerd - All things LEGO and the LEGO fan community