Item Relationships

Items in the catalog that have something in common beyond their placement in categories have been grouped together into relationship matches. For example, a left-side door can be matched to a right-side door. Left/right pairing of items is one type of relationship match.

BrickLink uses 18 different types of item relationships as described below. You may add new relationships to existing items or add new items to existing relationships using the Add New Relationship form. You may find relationship numbers for existing relationships and see all item relationships by visiting the Item Relationships page.

  • Similar Sets with Same Numbers - Matches similar sets that have two or more catalog entries with the same item numbers (9680-1 and 9680-2, for example).

  • Similar Sets with Different Numbers - Matches similar sets with different set numbers that may include different packaging materials, package graphics, and some parts or aspects of parts. These differences are frequently related to geographic area and time of release. Matches may include sets with the same set number distinguished by different BrickLink suffix numbers only in cases of three or more set versions, when some have the same set number and some do not.

  • Similar Gear with Different Numbers - Matches similar items in the Gear item type that include different package identification numbers and may include different packaging materials, package graphics, and some parts or aspects of parts. These differences are frequently related to geographic area and time of release. Electronics and video games may include differences in platforms or format.

  • Similar Parts with Different Molds - Matches variations over time in mold design or molding process. These variations between otherwise similar parts can create a different appearance or function of parts, or may have no real effect on how the parts appear or are used. Examples of matches include increased strength, unobtrusive functional additions, and structural improvements for ease of use. This match excludes cases of variation in the same applied pattern and generally excludes matching part molds that are intentionally designed to be different parts. Examples of exclusions are parts with one clip attachment versus two clip attachments, pin holes versus axle holes, and differing spoke arrangements for wheels.

  • Same Books in Different Languages - Matches books that have essentially the same content, but which were published in different languages.

  • Same Gear in Different Languages - Matches items in the Gear item type that have essentially the same content, but which were published in different languages.

  • Same Items with Similar Patterns - Matches subtle changes over time to what is essentially the same pattern applied to what is essentially the same part, including changes to pattern colors for otherwise identical patterns. Different methods of pattern application are included, such as printed or decorated with a sticker.

  • Same Stickers with Different Catalog Entries - Matches identical sticker sheets that appear in either two sets or in three sets.

  • Figure In-Set Variants - Matches figures that varied in sets with the same set numbers. An example is a figure with a solid stud head that later appeared in the same set with a blocked open stud.

  • Figure Stickered and Non-Stickered Matches - Matches figures without a sticker to otherwise identical figures with a sticker or stickers applied.

  • Door on Door Frame - Matches doors with the door frames they fit. This relationship type also includes items from other categories that may be considered a door frame in nature, such as a furniture cupboard.

  • Glass on Door Frame - Matches glass panes with the door frames they fit. This relationship type also includes items from other categories that may be considered a door frame in nature, such as a furniture cupboard.

  • Glass on Window - Matches glass panes with the window frames they fit. This relationship type also includes items from other categories that may be considered a window in nature, such as a vehicle canopy.

  • Tire on Wheel - Matches tires and tread with the wheels they fit. This relationship type also includes items from other categories that may be considered a wheel in nature, such as a Technic gear, when those items are used as wheels in set instructions.

  • Paired Parts - Matches items that are normally associated with another similar item to make up a left and right pair. An example is left and right doors. These parts are not normally attached to each other in any natural way, but are often used together. They are essentially mirror images of each other, but the match may also include two or more parts that form a complete pattern when used together.

  • Parts that Belong Together - Matches parts designed to naturally work with each other that are nearly always used together as a single unit, typically while attached together in some way. This match excludes parts otherwise eligible for inclusion when they are used in multiple combinations. Two examples of such exclusions are a horse saddle used for several different horses and a turntable base used with several different kinds of tops.

  • Unsplit Part Variants - This is not actually a relationship match because it does not match two parts. Instead, it is a way to keep track of mold and print variants for parts that have not yet been split into different catalog entries. These parts may or may not be split in the future. Each new match added must include only a single part. Variants are only added for the basic part and not for all the assemblies in which that variant occurs.

  • Sets Redesigned During Production - This is not actually a relationship match because it does not match two items. Instead, it is a way to keep track of sets redesigned during the time the set was manufactured. To be considered a redesign the changes to the set must be reflected in the instructions and involve a change in quantity or color for at least one part in the Regular Items section of the inventory. Each new match added must include only a single set.