(a) Measuring devices. The appropriate TTB officer may at any time require proprietors to provide at their own expense equipment for ascertaining the capacity and contents of tanks and other storage containers, and scales and measuring devices for weighing and measuring wine, spirits, volatile fruit-flavor concentrate, or materials received and used in the production or treatment of wine. Where winemaking materials or other materials used in the treatment of wine are used immediately upon receipt on wine premises, or received and stored on bonded wine premises in original sealed shipping containers with a stated capacity, the quantity shown on the commercial invoice or other document covering the shipment may be accepted by the proprietor and entered into records in lieu of measuring the materials upon receipt.

(b) Testing instruments. The proprietor shall have ready access to equipment for determining the alcohol content unless the proprietor only receives and stores on wine premises bottled or packed wine with evidence showing the alcohol content has been determined. The proprietor who bottles or packs wine shall have ready access to equipment for determining the net contents of bottled or packed wine. The appropriate TTB officer may require other testing instruments based upon the proprietor's operations.