Here are two reviewa on 21700 5000mah batteries, link is:
https://budgetlightforum.com/node/76779 or https://budgetlightforum.com/node/76591
Specifications
Battery type: 21700
Battery Capacity: 5000mAh(Standard), 4900mAh(minimun)
Battery Voltage:3.6V
MAX Discharge Current: 10A (but it can handle max 15A)
Data below is from a test review on BLF. CLICK ME to check details.
Diameter: 21,7mm ± 0,2mm
Length: 70,9mm ± 0,2mm
Weight: 72g ± 4g
Nominal capacity: 5000mAh at 0.2C discharge current
Minimum voltage: 2.50V
Maximum voltage: 4.20V ± 0.03V
Standard charge current: 0.2C (1000mA)
Maximum charge current: 0.7C (3500mA)
Maximum discharge current: 2C (10000mA)
Initial internal impedance: ≤ 30mΩ