Ulanzi ST-09 Cage for iPhone Review: Turn Your Phone into a Cinema Rig

The Ulanzi ST-09 Cage for iPhone has 8,900+ reviews on JD.com with a 4.4/5 rating at ¥199 ($28). Users love the precise cutouts for button access, the multiple cold shoe mounts for accessories, and the metal build quality. The main complaints are that it adds bulk, the spring tension on the clamp can mark phones, and the included lens mount isn’t as secure as dedicated filter holders. Conclusion: ✅ Worth Buying — the best affordable phone cage for mobile filmmakers.

Introduction

Smartphone videography has matured to the point where iPhones and flagship Android devices can produce cinema-quality footage with the right accessories. The Ulanzi ST-09 Cage is designed to bridge the gap between phone and rig — providing mounting points for microphones, LED lights, and lenses while protecting the phone and improving handling.

With nearly 9,000 reviews on JD.com, the ST-09 is one of the best-selling phone cages in China. It competes with the SmallRig Phone Cage, PGYTECH Phone Mount, and BeastGrip at a fraction of the price. At ¥199, it’s the most affordable serious phone rig on the market.

Specifications

Specification	Ulanzi ST-09	SmallRig Phone Cage	PGYTECH Phone Mount	BeastGrip Pro
Price	¥199 ($28)	¥329 ($46)	¥249 ($34)	¥1,299 ($180)
Material	Aluminum alloy	Aluminum alloy	Aluminum + plastic	Aluminum alloy
Compatibility	iPhone 15/16 Pro Max	Universal (adjustable)	Universal (spring)	Universal (screw)
Cold Shoe Mounts	4	3	2	3
Filter Thread	37mm (with adapter)	37mm	None	37mm
Tripod Mount	1/4-20 (×4)	1/4-20 (×3)	1/4-20 (×2)	1/4-20 (×2)
Lens Mount	17mm thread (included)	17mm thread	None	17mm thread
Weight	95g	120g	75g	180g
Grip	Wooden side grip	Rubberized	Textured plastic	Metal + grip
JD Rating	4.4/5	4.5/5	4.3/5	4.5/5

Design and Build Quality

The ST-09 Cage combines a spring-loaded clamp mechanism with a rigid aluminum alloy frame. The clamp adjusts to fit most phone widths, with silicone pads protecting the phone’s edges and back from scratches. The frame wraps around the phone securely, providing 4 cold shoe mounts (2 on top, 1 on each side) for accessories. The 1/4-20 threaded mounting points on the bottom and sides allow attachment to tripods, gimbals, and light stands.

The standout feature at this price is the wooden side grip — a small piece of solid wood on the left handle that provides a more comfortable and natural hold compared to standard rubberized grips. The included 37mm filter adapter and 17mm lens mount system allow attachment of ND filters, wide-angle lenses, and anamorphic adapters. Build quality is impressive for ¥199 — the aluminum is well-machined, all threads are clean, and the clamp mechanism operates smoothly.

“The wooden grip is surprisingly comfortable — much nicer than the rubber grips on other cages I tried. The cage fits my iPhone 16 Pro Max securely without any rattle. Four cold shoe mounts let me run a wireless mic, LED light, and monitor all at once.” — Huang Fang, JD.com Verified Purchase, 5-star review

Performance

In practical shooting, the ST-09 transforms the iPhone from a slippery, awkward filming device into a proper rig. The added mounting points allow a complete mobile video kit — wireless microphone on one cold shoe, small LED panel on another, and a monitor or phone holder clamp on the top. The cage provides a secure hold for gimbal use, though some larger gimbals may require rebalancing with the added weight.

The 37mm filter thread accepts standard screw-on ND filters, polarizers, and diffusion filters — dramatically improving video quality control on a smartphone. The included wide-angle lens adds versatility for establishing shots and tight spaces. The tripod mount threads on the bottom allow quick mounting on any standard tripod or monopod, and the side 1/4-20 threads enable horizontal rigging configurations.

“I use this cage with my iPhone 16 Pro and a Rode VideoMic Go for interview shoots. The cage holds everything securely and the cold shoe mounts keep cables organized. The filter thread lets me use my existing ND filters — a huge improvement over clip-on filter systems.” — Zhou Kai, JD.com Verified Purchase, 5-star review

What Chinese Users Say

On Build and Value: “For ¥199, the build quality is shocking. The aluminum frame, wooden grip, included lens and filter adapter — it’s a complete kit. My friend paid ¥1,299 for a BeastGrip and honestly the difference isn’t 6x.” — JD.com user, 5 stars 💡 Exceptional value for a complete cage kit.

On Spring Tension: “The spring is tight, which is good for secure grip. But if you’re not careful when inserting/removing the phone, the metal edge can scratch the frame. A small concern but worth being careful.” — TMall user, 4 stars 💡 Care needed during phone insertion to avoid scratches.

On Accessory Compatibility: “The 37mm filter thread is great but note that heavier filters (variable ND, large polarizers) can be top-heavy on the phone. Use lighter filters or support the lens adapter arm.” — JD.com user, 4 stars 💡 Weight balance matters with heavier accessories.

On Gimbal Use: “I use this with my DJI OM 6. The cage adds enough weight that you need to balance the gimbal carefully. Works once balanced but the added convenience of mounting accessories is worth the setup time.” — Taobao user, 4 stars 💡 Gimbal balancing required with cage attached.

Pros and Cons

Pros

• Affordable price for a complete cage kit
• Aluminum alloy construction with wooden grip
• 4 cold shoe mounts for extensive accessories
• 37mm filter thread for ND/polarizer filters
• Includes wide-angle lens adapter
• Multiple 1/4-20 tripod mounting points
• Secure clamp with silicone padding

Cons

• Spring tension can mark phone edges if not careful
• Adds noticeable bulk to phone size
• Heavy accessories can create balance issues
• Lens mount adapter isn’t as stable as dedicated systems
• Not compatible with larger battery cases

FAQ

Q1: Does the ST-09 fit iPhone 16 Pro Max with a slim case?

The cage is designed for bare phones. With a case, the clamp may not secure properly. It’s recommended to remove the case before mounting, or check compatibility with your specific case thickness.

Q2: Can I use wireless charging with the cage on?

No, the cage covers the back of the phone and blocks wireless charging. MagSafe accessories will also not work directly through the cage.

Q3: What filters work with the included 37mm adapter?

Any standard 37mm screw-in filter works. For thicker filters (like variable ND or step-up rings), the included lens mount arm provides additional support.

Q4: Does the cage interfere with iPhone camera controls?

The cage design includes cutouts for the camera control button, action button, volume buttons, and side switch on supported iPhone models. All controls remain accessible.

Q5: Can I use this cage with Android phones?

The ST-09 is designed specifically for iPhone dimensions. For Android phones, Ulanzi offers universal adjustable cages. The spring clamp adjusts to various widths but the corner cutouts may not align perfectly with all Android devices.

Verdict and Rating

The Ulanzi ST-09 Cage for iPhone is proof that you don’t need to spend a fortune to build a serious mobile video rig. At ¥199, it provides the essential features of phone cages costing 5-10x more: secure fit, multiple mounting points, filter compatibility, and tripod connectivity. The wooden grip is a thoughtful touch that genuinely improves handling.

The spring tension and bulk are the main compromises, and gimbal users will need to rebalance. But for desk-based recording, tripod shooting, and handheld mobile content creation, the ST-09 transforms an iPhone into a capable video production tool at an unbeatable price.

Overall Rating: 4.4/5

• Build Quality: 4.5/5 — Aluminum alloy at this price is impressive
• Versatility: 4.5/5 — 4 cold shoes, filter thread, multiple mount points
• Value: 5/5 — Best-in-class for the price
• Handling: 4.0/5 — Wooden grip is excellent, but bulk is noticeable
• Accessory Support: 4.0/5 — Good but not as stable as premium cages