LEGO Transparent Medium Blue Glass for Window 1 x 4 x 3 (without Circle) (3855)

LEGO Transparent Medium Blue Glass for Window 1 x 4 x 3 (without Circle) has been used in at least 2 LEGO sets over the past 21 years, since it was first used in 2003. You can also find this part in at least 10 other colors. It has a design ID of 3855 which can usually be found molded into the bottom of the part.