BPTs

All pools in Balancer are also ERC20 tokens known as BPTs (Balancer Pool Tokens), which represent proportional ownership in the pool's liquidity. When users add liquidity through joinPool or joinswap* they receive BPTs proportional to the amount of assets they are adding to the pool.

Notes

BPTs are an opinionated ERC20 token implementation, and have a few subtle differences. transferFrom from itself does not require a previous allowance.