 To become a distributor there is an initial buy-in and an emphasis on the necessity of recruiting other people in order to receive commissions.This follows the structure of multi-level marketing, although there are recruiting bonuses after three retail sales a month as an incentive to grow the sales force, the majority of the cash-flow is said to be generated by commissions on sales.An example of a recognised independent testing program to "evaluate aftermarket retrofit devices which claim to improve automotive fuel economy and/or reduce exhaust emissions" is that run by the US Environmental Protection Agency (EPA) identified by test program authorities 42 USC 7525 and 49 USC 32918, and formerly known as the "511 Program".