Frequently Bought Together
The small parts behind a big idea. These chrome ball connectors and expansion tube connectors are the joints of USM Haller style modular furniture: a ø25 mm ball threaded M8 on six faces, and a ø16 mm connector that locks inside a ø19 mm tube. Order them as spares, or as a complete kit for a side table or nightstand frame.
About the USM Haller System
In 1963, Swiss engineer Paul Schärer and architect Fritz Haller reduced furniture to three elements: a steel tube, a panel and a small chromed ball. Because the ball is threaded on six faces, a tube can leave it in any direction, so the same joint works at the corner of a single cube or in the middle of a wall of shelving. That one idea made the USM Haller system endlessly reconfigurable and carried it into the permanent collection of the Museum of Modern Art. These connectors follow the same construction principle as the pieces in our USM Haller style family: the ball is the node, and an expansion connector hidden inside each tube end bolts the frame to it. A handful of them is enough to replace a tired joint, extend a frame by another bay, or build a new piece around tubes cut to your own measurements.
Materials & Craftsmanship
- Ball connector: a ø25 mm (1") chrome-plated metal ball, drilled on all six faces and tapped M8 — the node that lets a frame grow in any direction
- Expansion tube connector: ø16 mm × 30 mm (0.63" × 1.2"), made of three parts — a slotted sleeve, a split expanding core and a black M8 hex-socket screw
- How it holds: the connector slides into the end of a ø19 mm (¾") round metal tube; as its screw is tightened into the ball, the connector expands against the inside wall of the tube for a rigid joint
- Hidden hardware: once assembled, the connector sits inside the tube, so only the chrome ball and the tubes remain visible
- Hex key included: every set comes with the hex key used to tighten the screws
What's in Each Set
- Ball Connector 4-Pack: 4 ball connectors — spares, repairs, or the extra nodes needed to extend a frame
- Expansion Connector 3-Pack: 3 expansion tube connectors — spares or replacements for individual tube joints
- Side Table Kit: 8 ball connectors + 24 expansion tube connectors — everything that joins one cube frame (8 corners, 12 tubes)
- Nightstand Kit: 12 ball connectors + 40 expansion tube connectors — everything that joins a two-tier frame (12 corners, 20 tubes)
Every set includes a hex key. Tubes, panels and casters are not included.
Specifications
| Ball connector | ø25 mm (1") chrome-plated metal ball, M8 thread on six faces |
|---|---|
| Expansion tube connector | ø16 mm × 30 mm (0.63" × 1.2"), M8 hex-socket screw |
| Fits | ø19 mm (¾") round metal tube |
| Thread | M8 |
| Tool | Hex key included with every set |
| Not included | Tubes, panels, casters |
Care & Assembly
Seat an expansion connector in each tube end, thread it into the ball and square up the frame before tightening with the included hex key — as the photos show, the key can reach a connector's screw through the opposite hole of the ball. Tighten until the joint is firm; snug is enough. Check the joints again after the first few days of use and whenever a piece is moved. Keep the chrome balls bright with a dry microfiber cloth, and avoid abrasive cleaners or scouring pads, which can scratch the plating.
Frequently Asked Questions
What tube size do these connectors fit?
They are made for ø19 mm (¾") round metal tubing. The connector measures ø16 mm before it expands, so check that the inside diameter of your tube is about 16 mm.
Are tubes and panels included?
No. Each set contains connectors only — ball connectors, expansion tube connectors or both — plus a hex key. Tubes, panels and casters are not part of these sets.
Which kit do I need for a side table or a nightstand?
A single cube frame has 8 corners and 12 tubes, so it takes 8 ball connectors and 24 expansion tube connectors — the Side Table Kit. A two-tier frame has 12 corners and 20 tubes, so it takes 12 ball connectors and 40 expansion tube connectors — the Nightstand Kit.
Will they work with original USM Haller furniture?
These connectors are made for USM Haller style furniture built on ø19 mm tubes and M8 ball joints, such as our own side table and bar cart. They are not manufacturer replacement parts, and thread sizes and tolerances can differ between makers, so measure your existing ball thread and tube before ordering.
Do I need any tools?
Only a hex key, and one is included with every set.
How do I keep the chrome looking new?
Dust the balls with a dry microfiber cloth and wipe away fingerprints with a barely damp one, drying straight away — see Care & Assembly above.
Explore the USM Haller Style Family
These connectors belong to our USM Haller style family. See the pieces built on the same chromed tubes and ball joints: mobile side table on casters, bar & serving cart, nightstand with storage and TV stand media console.
Shipping & Returns
Free US shipping with door-to-door delivery and 30-day returns — see our shipping policy and return policy.
| Set |
Ball Connector 4-Pack, Expansion Connector 3-Pack, Side Table Kit (8 Balls + 24 Connectors), Nightstand Kit (12 Balls + 40 Connectors) |
|---|
