In 1956, LEGO released 7 System i Leg Supplemental sets, all of these sets have been retired.
Most valuable 1956 LEGO System i Leg Supplemental set
231-2 Esso Pumps and Sign $129.61
Largest 1956 LEGO System i Leg Supplemental set
224 2x2 & 2x4 Curved Bricks 14 pieces
Theme / Subtheme System i Leg / Supplemental
Year 1956
Pieces 14
Availability Retired
224 LEGO 2x2 & 2x4 Curved Bricks
Retail $0.50
Theme / Subtheme System i Leg / Supplemental
Year 1956
Pieces 2
Availability Retired
231-2 LEGO Esso Pumps and Sign
Retail $0.50
Value $129.61
Growth  +25822.0%
Annual growth 7.4%
Theme / Subtheme System i Leg / Supplemental
Year 1956
Pieces 4
Availability Retired
1226-2 LEGO 6x8 & 2x8 Plates
Theme / Subtheme System i Leg / Supplemental
Year 1956
Pieces 5
Availability Retired
1227-2 LEGO 4x8 & 2x8 Plates
Theme / Subtheme System i Leg / Supplemental
Year 1956
Pieces 6
Availability Retired
1228-2 LEGO 4x8 Curved & 2x8 Plates
Retail $0.50
Theme / Subtheme System i Leg / Supplemental
Year 1956
Pieces 10
Availability Retired
1231-2 LEGO Red Windows and Door with Glass
Theme / Subtheme System i Leg / Supplemental
Year 1956
Pieces 10
Availability Retired
1231-3 LEGO White Windows and Door with Glass