LEGO 1231 Red Windows and Door with Glass is a vintage System i Leg set from 1956 valued at $2 for new and sealed sets, up 105% from an original retail price of $1.00. Annual appreciation has averaged 1.32% since release. Used copies are valued between $2 and $2 depending on condition.
LEGO 1231-2 Red Windows and Door with Glass is a System i Leg Supplemental set released in 1956, containing 10 pieces. It was distributed exclusively in Denmark. The set includes red glazed building elements from the 1950s era, featuring hinged 1 x 2 x 3 doors and a range of windows with fixed glass in sizes such as 1 x 1, 1 x 2, 1 x 3, 1 x 4, 1 x 6, and a 1 x 6 x 3 panorama window, reflecting early extended-lip and solid-stud designs. It is similar in concept to set 214-2 Ten Windows and Doors, Red, and was a supplemental pack.
A new and sealed Red Windows and Door with Glass is currently valued at around $2, with annual growth of approximately 1%, which is lower than other Supplemental sets. The average used price is $2 for those in good overall condition. Based on current trends, this set could be valued near $2 within the next year.