They are based in China
As the name says they have BMS, pretty good ones.
They also stock some interesting battery cells with not terrible prices.
https://bmsbattery.com/65-battery-cell
Need ebike parts? They got 'em
Also a convenient place to get a ST-Link
Last thing is chargers. What in the watt
https://bmsbattery.com/13-ebike-charger-ev-charger
Not too bad
What do you think?