Certification marks differ from collective trade marks. Collective trade marks may be used by particular members of the organization that owns them, while certification marks are the only evidence of the existence of follow-up agreements between manufacturers and nationally accredited testing and certification organizations. In some occasions, the certification organization will charge for the use of their labels and will require that the manufacturer reports the exact production quantities. In this case, the certification organization can be seen to earn a commission from sales of products under their follow-up regimes. In return, the use of the certification marks "enables" the product sales in the first place.