Just found your question about WUBEN T70 and A21. All difference I can gather as follows:

1. A21 is compatible with 18650 battery and comes with a tube to use 18650. While T70 only powered by 26650
2. The size is a bit different, A21 is 135.5mm*42mm, while T70 is 13.7mm*42mm
3. A21 is 12854cd, T70 is 15750cd
4. The weight is different too. A21 218g with battery, T70 is 261g with battery.
5. T70 has an extension tube to use 2pcs battery for doubling runtime, while A21 is not.
6. A21 has an eco mode of 5lm, while T70 is not.

A21 is running a groupbuy on BLF now. Groupbuy price: 99.84 USD in 20% OFF, code: WUBENA21
link: https://www.amazon.com/s?me=A2JFZQPTWASL74&marketplaceID=ATVPDKIKX0DER

T70 extension tube link: Amazon.com