KingSmith X21 Folding Treadmill
A double-folding running treadmill with a larger console, quick speed keys and NFC pairing. Built for regular training rather than occasional walking.
What it changes
Bought once, not billed monthly. A US gym runs $40–70 a month, every month, whether you go or not. This is one payment, and it stays in your home.
The drive costs more than the fee. Two sessions a week is an hour in traffic and fuel you didn't plan on. Here the commute is the length of a hallway.
Your evenings come back. 6 a.m. or 10 p.m., twelve minutes or fifty. Nothing has to be booked, and nothing closes.
Built to outlast the payback. Optional protection from Consumer Priority Service picks up after the one-year manufacturer warranty, for up to six years of total coverage.
Why you'll love it
- A real training treadmill that still folds away. 1.25 HP, 7.5 mph, an 18.1 in belt, and a double fold that stores it in a closet.
- Speed on one key. Quick speed buttons jump straight to your interval pace instead of tapping up one step at a time.
- Tap to pair. NFC on the console connects your phone to the KS Fit app with a touch. Apple Watch supported.
- See your pace from the deck. Enlarged console plus the interactive light strip along the belt.
Specifications
| Motor | Brushless 1.25 HP / 918 W |
|---|---|
| Speed range | 0.6–7.5 mph (1–12 km/h) |
| Running surface | 47.6 × 18.1 in (121 × 46 cm) |
| Maximum user weight | 243 lb (110 kg) |
| Product weight | 82 lb (37 kg) |
| Shipping weight | 93 lb (42 kg) |
| Folding | Double fold |
| Console | Enlarged display panel |
| Quick speed adjustment | Yes |
| NFC | Yes |
| Interactive light | Yes |
| Armrest | Yes |
| Transport wheels | Large wheels (ø 51 mm) |
| Display | Time, speed, distance, calories, steps |
| App | KS Fit (iOS and Android) |
| Apple Watch | Supported |
| Overload protection | Yes |
| Incline | Not available |
| FCC ID | 2AR7VC-8082U |
Model TRX21F. Specifications are supplied by the manufacturer and may be updated without notice.
Frequently asked questions
Tap a question to open the answer.
▸ X21 or X25 — which should I get?
X21: 7.5 mph, 243 lb, 82 lb frame. X25: 9.9 mph, 300 lb, 1.5 HP, 104 lb frame. If you run intervals above an 8-minute mile or weigh over 240 lb, the X25. Otherwise the X21 does the job for less.
▸ What do the quick speed keys do?
They jump straight to preset speeds, so you go from a walk to your run pace in one press. Useful for intervals.
▸ What is the NFC for?
Hold your phone to the console and the KS Fit app pairs instantly, no Bluetooth menu. Your sessions then sync to the app, Apple Health and Apple Watch.
▸ Can I use it as a walking pad under a desk?
Yes. Fold the handrail down for walking mode. It's taller than a dedicated pad, so check desk clearance.
▸ How big is it when folded?
The handrail folds onto the deck and the deck folds in half, so the stored length is roughly half of the 47.6 in belt length. It fits in a closet or behind a door and rolls on large wheels.
Delivery
Free delivery to addresses in the 48 contiguous United States and the District of Columbia. Orders are dispatched within 48 hours of payment from our US warehouse and typically arrive within 2 to 6 working days. Tracking is emailed on dispatch. We do not currently ship to Alaska, Hawaii or Puerto Rico.
Warranty and returns
Every X21 comes with a 12-month limited warranty covering the motor, electronic controller, main frame and console. The full terms are in our warranty policy.
Returns are accepted within 30 days of delivery in original packaging. Items delivered between 1 November and 31 December may be returned within 45 days. See our refund policy for the full terms.
Optional extended protection
You can add an extended protection plan from Consumer Priority Service (CPS), our warranty partner, when you order. It begins where the 12-month manufacturer warranty ends and can take total coverage up to six years.
- One single payment — never a monthly rate. You pay once at checkout. There is no subscription, no recurring charge and nothing to cancel later.
- 100% of parts and labor for mechanical and electrical failure, including manufacturing defects and hardware failure.
- Home and commercial use are both covered — the plan is valid whether the treadmill sits in your bedroom or in an office.
- If it cannot be repaired, it gets replaced.
Pick your term from the protection plan option shown with this product or in your cart. It is entirely optional, and the 12-month manufacturer warranty applies either way. Accidental damage is not covered by this plan.
Still deciding? Compare the range
Easiest to control mid-run — you're on it
KingSmith X21 — the training treadmill that still folds into a closet.
Quick speed keys and NFC pairing turn an interval session into single presses instead of held buttons and menus. The trade-off: the lowest top speed and weight rating in the X-series.
If you train faster than an eight-minute mile
KingSmith X214 — the same double-folding frame with more top-end speed and full side armrests. Best if tempo runs are a regular part of your week. See the X214 →
If you're a heavier runner
KingSmith X25 — a stronger motor and a higher weight rating, in a frame one person can still roll away. Best if you want the capacity without the flagship's bulk. See the X25 →
If storage space is the real constraint
KingSmith MX10 — the same double fold on a lighter, slower frame. Best if the machine has to disappear between sessions. See the MX10 →
If you want one machine for the desk and for running
WalkingPad R3 Hybrid+ — a wide deck that goes flat for the desk and opens into a treadmill afterwards. Best if you'd otherwise buy a pad and a treadmill. See the R3 Hybrid+ →
Complete your setup
🚚 Shipping & Returns
Free US shipping on every order · estimated delivery 2 to 6 business days · tracking link by email when it ships.
30-day Buyer Protection — damaged, defective or incorrect items are covered with a free replacement or refund. See FAQ →
12-month manufacturer warranty — covering defects in materials and workmanship. Read the warranty policy →