The recipients of the Bond tokens are the lenders who lent the underlying ERC20 asset tokens into the Principal pool. Bond tokens essentially accounts for the Principal plus interest owed after maturity to the lenders. An owner of the Bond tokens can burn them after the maturity date, to withdraw the exact same amount of the underlying asset tokens in the Principal pool. For example, consider a user who owns 30 Bond tokens of a DAI/WETH pool expiring on 12-30-2021. Assuming a total supply of 500 Bond tokens held by all the lenders and a total of 1200 DAI assets in the Principal pool, the user, then, can swap his tokens for 30 DAI after 12-30-2021.