21st Scooter started OEM for some foreign scooter brands in 1998 until 2012, when it created its own brand and entered the domestic market. 21st Scooter's products are priced under $300. Relying on the low-price strategy, the brand quickly opened up the market and sold a considerable amount.
 
21st Scooter does not have a uniform product name, it can only be distinguished by article number. RO203M-3 and RO203M-5 are two products with similar designs. Like the Micro Deluxe, the toddler scooters look like a 2-wheel-1 rear wheel at first glance, but the rear wheels are actually made up of two 100mm wheels side by side. The benefit is greater stability and less tilt due to imbalance. The RO203M-3 has 3 height adjustments from 67 cm to 90 cm, making it suitable for children from 2 to 8 years old. The height adjustment of RO203M-5 is not limited to gears, which can be flexibly adjusted according to the height of the child. Both the RO203M-5 and RO203M-3 are non-collapsible, but parents can remove the riser to save storage space.
 
Compared to the previous two products, the higher-priced RO203L and D3 are more functional. The RO203L has a steering angle of less than 20 degrees and a rebound design to help children quickly regain their balance after cornering, but the design also increases the amount of force required when steering. Compared to the RO203L, the D3 shines with its shock absorption system and spring protective case on the front end. These two designs allow the impact to be effectively cushioned in the front of the bike, making it safer and more comfortable for children to ride. In terms of portability, the RO203L has a foldable design with the riser folded onto the pedals. The D3, on the other hand, can remove the riser and put it into the storage slot under the car, which is rare in three-wheeled scooters, which is an innovation of the manufacturer, but it may also weaken the strength of the floor.
 
The low pricing allowed 21st Scooter to quickly open up the market, but its products have certain flaws in workmanship, and burrs can be seen in welds, buckles, plastic joints and other parts. In addition, in the 2017 sampling inspection of the Hong Kong Consumer Council, 21st Scooter's products were found to have high levels of PAHs (mainly on the handles), and parents are advised to let their children play outdoors and other ventilated places, and use soap or hand sanitizer to wash their hands after riding scooters.