Now I sum up three difference among 21700 kit and 20700 kit, see the picture:

Parameters
Mod
Size: 46.03*37.10*81.50mm
Weight: 297g
Thread Type: 510 spring loaded connector
Cell Type: high-rate 21700/18650 cell
Output Wattage: 1-230W
Resistance Range: 0.05-1.5ohm for TC modes
0.1-3.5ohm for VW mode
Temperature Range: 100-315°C/200-600°F (TC modes)
Maximum Charging Current: 2A
Maximum Output Current: 50A
Output Voltage Range: 0.5-9V
Atomizer
Height: 45mm
Diameter: 25mm
Weight: 51.8g
E-liquid Capacity: 2ml
Features
1. 230W Max Output with Dual 21700/18650 Cells
2. Humanized Push-pull Design for Conenient Exchange
3. Powerful WM Coils for Huge Vapor and OPtional Flavor
4. Two Versions of E-liquid Capacity and Drip Tips Available
5. 2A Max Charging Current for Quick Charge
6. Dual Circuit Protection & Reverse Polarity Protection
7. Retractable Top Filling Solution & Convenient Bottom Airflow Control

See more info in https://vapesourcing.com/wismec-reuleau ... l-kit.html" onclick="window.open(this.href);return false;
if you want buy 20700 kit, click here: https://vapesourcing.com/wismec-reuleau ... l-kit.html" onclick="window.open(this.href);return false;