LEGO Classic 1x1 Brick Multicolor Changing Integrated LED Silicone Night Light, Green LP41 - The Home Depot
Identify brick with internal battery, light and sound - Bricks
BrickLink - Part 54930c02 : LEGO Electric, Light Brick 2 x 3 x 1 1/3 with Trans-Clear Top and Yellow LED Light (Glows Orange) [Electric, Light & Sound] - BrickLink Reference Catalog
LED Lighting Kit - Colored Battery Bricks for LEGO sets - 7 pack with all colors - Walmart.com
LEGO Classic 1x1 Brick Multi-Color Changing Integrated LED Silicone Night Light, Yellow LP42 - The Home Depot