Classic Spacers, Caps & Locks
Last checked: 24 August 2026
Classic K’NEX spacers, caps and locks are small parts used to position, retain, protect or secure other parts on Classic K’NEX rods.
Although these parts may look similar in use, they perform different functions:
- Spacers create and maintain space between parts on a rod or axle.
- Caps fit at the end of a rod.
- Locks secure a connection or help prevent it from coming apart.
Some Classic K’NEX clips can also be used as stops or retaining parts. These remain part of the Classic Clips family and are referenced separately below.
Spacers
Spacers slide onto a Classic K’NEX rod. They are particularly useful on axles, where they help keep wheels, gears and other moving parts in the required position.
There are two basic physical forms: ring-shaped spacers and a wider tube-shaped spacer.
Spacer rings
The Blue and Light Grey spacers are narrow ring-shaped parts.
| Colour | Part number | Form |
|---|---|---|
| Blue | 90994 | Spacer ring |
| Light Grey | 91994 | Spacer ring |
The Light Grey 91994 has the same dimensions as the Blue 90994. It is therefore a colour/part-number variant rather than a different spacer size.
Multiple spacer rings can be placed next to each other when more spacing is required.
Spacer tube
| Colour | Part number | Form |
| Silver | 91224 | Spacer tube |
The Silver spacer is wider and looks more like a short piece of tube than a narrow ring.
It performs the same general spacing function, but occupies considerably more space along the rod than a single spacer ring.
This makes it useful when a larger fixed space is required between components without using several individual spacer rings.
Caps
Caps are fitted at or over the end of a Classic K’NEX rod.
Different cap designs can protect the end, retain another component or provide a finished end to a construction.
Snap cap
| Colour | Part number |
| Black | 848900 |
The 848900 Snap cap fits onto the end of a Classic K’NEX rod.
Because it is fitted at the rod end, it can also perform a retaining or stopping function depending on the construction.
End cap
The 23692E End cap is another Classic rod-end component.
Known colours include:
| Colour | Part number |
| Black | 23692E |
| Blue | 23692E |
| Green | 23692E |
| Yellow | 23692E |
| Orange | 23692E |
The same basic part number is therefore encountered in several colours.
Locks
Rod lock
| Colour | Part number |
| Black | 91660 |
The Classic Rod lock 91660 is used to secure a rod-to-connector connection.
Unlike a spacer, which slides onto a rod to establish a position, the Rod lock is specifically intended to help keep a connection secured.
This can be particularly useful in constructions where rod-to-connector joints are subjected to greater loads or movement.
Spacing, stopping and locking are different functions
These functions can overlap, but they should not be treated as identical.
Spacing
A spacer determines the position of components along a rod or axle.
Stopping or retaining
A component prevents another part from moving beyond a particular position or from sliding off the end of a rod.
Locking
A lock helps secure a connection so that the connected parts are less likely to separate.
This distinction also explains why some parts from other Classic K’NEX families can perform a similar function without becoming spacers, caps or locks.
Related Classic Clips
Several Classic Clips can also perform stopping, retaining or locking functions.
They remain classified as Classic Clips because their construction and primary part type are clips.
Clip used as an end stop
91440 — Clip — Blue
914401 — Clip — Bronze
These clips can be fitted at the end of a rod or axle. One common use is to prevent a wheel from sliding off.
See Classic Clips for the complete clip family.
Interlocking clips
90900 — Interlocking clip — Tan
91900 — Interlocking clip — Bronze
Interlocking clips can be used to retain or position components such as wheels or gears on a rod.
Their locking function makes them relevant here, but they remain part of the Classic Clips family.
Not every “snap-on” part is a cap
The word snap or snap-on can also describe how another K’NEX part attaches.
For example, some Classic gears are described as Snap-on gears. These are gears, not caps, and are therefore documented with Classic Gears.
The name Snap cap, by contrast, identifies the 848900 cap itself.
Quick reference
| Type | Colour | Part number |
| Spacer ring | Blue | 90994 |
| Spacer ring | Light Grey | 91994 |
| Spacer tube | Silver | 91224 |
| Snap cap | Black | 848900 |
| End cap | Black | 23692E |
| End cap | Blue | 23692E |
| End cap | Green | 23692E |
| End cap | Yellow | 23692E |
| End cap | Orange | 23692E |
| Rod lock | Black | 91660 |
Related retaining and locking clips
| Type | Colour | Part number | Main family |
| Clip / end stop | Blue | 91440 | Classic Clips |
| Clip / end stop | Bronze | 914401 | Classic Clips |
| Interlocking clip | Tan | 90900 | Classic Clips |
| Interlocking clip | Bronze | 91900 | Classic Clips |
About this overview
This page documents known Classic K’NEX spacers, caps and locks and explains the differences between their functions.
Part names and numbers are based on documented K’NEX parts and are supplemented by known colour variants. Related parts from other families are included only as references and remain classified with their primary Classic K’NEX family.
Additional historical or uncommon variants may exist and can be added when they are reliably identified.
Last checked: 24 August 2026
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