ERG maintains an inventory of both exempt-quantity and licenseable radioactive check sources for rental on a weekly or monthly basis with order of other rental equipment. Sources are often required for daily function checks to identify consistent operation in field conditions. For alpha and beta instruments NIST-traceable alpha and beta check sources may be used to establish instrument efficiencies. Note: Th-230 check sources are available for short-term transfer pending review of an NRC or Agreement State radioactive materials license. Call for further discussion.