SO-101 profile: the $230 leader and follower pair

Contents

1. What is in the pair
2. What it records
3. Strengths and limits
4. Pricing
5. Questions to settle before buying
6. Sources

Type	Open-source leader-follower kit
Pricing	Published
Website	github.com

The SO-101 is the usual first rig for a team that wants to learn teleoperated data collection before spending real money. It was designed by TheRobotStudio with Hugging Face as the next generation of the SO-100, with improved wiring and easier assembly⁠1SO-ARM100: standard open arms SO-100 and SO-101 (bill of materials)TheRobotStudio on GitHub.

Best for: A first dataset and a first trained policy on the smallest budget, with software that records and uploads episodes out of the box.

Not the right fit for: Teams whose production robot is a different arm: demonstrations recorded on an SO-101 train an SO-101.

What is in the pair

Two arms. The follower uses six STS3215 servos, all geared 1/345. The leader uses six servos in three gear ratios, so that it carries its own weight and still moves under light force⁠2SO-101 assembly, motor setup and calibrationHugging Face LeRobot documentation. The published bill of materials is $229.88 for both arms in the United States, €226.30 in the European Union, and $121.94 for a follower alone; the servo itself is $13.89⁠1SO-ARM100: standard open arms SO-100 and SO-101 (bill of materials)TheRobotStudio on GitHub. Seeed Studio lists the arm at 5+1 degrees of freedom with a 500 g payload and 12-bit magnetic encoders, and sells a motor kit for both arms at $249.90 without printed parts⁠3SO-101 servo motor kit, LeRobot compatibleSeeed Studio.

What it records

LeRobot reads the leader’s joint positions as the action and the follower’s as the observation, alongside named camera streams, and saves them as a LeRobot dataset that uploads to the Hugging Face Hub by default. The recorder’s defaults are 60-second episodes, a 60-second reset and 50 episodes; the documentation suggests at least 50 episodes for a first task⁠4Imitation learning on real-world robots: teleoperate, record, trainHugging Face LeRobot documentation. The same library can drive the follower from a phone, using an iPhone app or Android WebXR⁠5Phone teleoperationHugging Face LeRobot documentation.

Strengths and limits

Strengths

• The lowest published entry price in this guide: $229.88 in parts for leader and follower, or $121.94 for a follower alone.
• Fully documented in LeRobot, from motor setup and calibration to recording, replay and training.
• Sold as kits and assembled arms by several vendors; Seeed Studio lists a motor kit for both arms at $249.90, without printed parts.

Limits

• It is its own small robot. Seeed Studio lists a 500 g payload, so it is a learning and research platform.
• The leader only drives an arm with the same joints; it is not a controller for an industrial arm.
• Parts must be printed and assembled unless an assembled arm is bought.

Choose another option if: You need to drive a Franka, UR or xArm (GELLO), or you want a supported bimanual station with a warranty (Trossen).

Pricing

$229.88 in parts for a leader and follower pair (US bill of materials); a motor kit without printed parts is $249.90 at Seeed Studio.

Questions to settle before buying

• Will the policy run on an SO-101, or is this a rehearsal for another arm?
• Who prints and assembles the parts, or is an assembled arm worth the premium?
• How many cameras does the task need, and where will they be fixed?
• Who will record the 50 episodes, and on what written protocol?

See how the SO-101 compares with the other options in the rig comparison table.

Sources

1. SO-ARM100: standard open arms SO-100 and SO-101 (bill of materials). TheRobotStudio on GitHub. Accessed 11 Nov 2026.
2. SO-101 assembly, motor setup and calibration. Hugging Face LeRobot documentation. Accessed 11 Nov 2026.
3. SO-101 servo motor kit, LeRobot compatible. Seeed Studio. Accessed 11 Nov 2026.
4. Imitation learning on real-world robots: teleoperate, record, train. Hugging Face LeRobot documentation. Accessed 11 Nov 2026.
5. Phone teleoperation. Hugging Face LeRobot documentation. Accessed 11 Nov 2026.

Further reading

• Buyer's guide · Updated quarterlyTeleoperation hardware in 2027: controllers, kits and rigs comparedNine ways to put a robot under a person's control, from a $230 pair of printed arms to a $24,000 bimanual station, compared on what they cost and what they record, followed by the line most hardware budgets leave out, the operators.
• Guide · Leader arms and kitsRobot teleoperation kits: SO-101, GELLO and the ALOHA line comparedA leader arm is the simplest teleoperation controller and the one that records the cleanest data. The kits differ by a factor of a hundred in price. This guide sets out what the money buys.
• ProfileGELLO profile: a printed leader arm for Franka, UR5 and xArmA replica of your robot arm, printed and assembled for under $300, that controls the real one joint for joint.