Proudly American
Find the part in the manufacturer's drawings
The DuraPlus instructions discuss its cap and spark-arrestor screen as part of that product family. Other chimneys use other configurations. A photograph from an invoice or the identifying name on the chimney paperwork can help the provider find the instructions without you approaching the roof.
Describe the reason for replacement
A torn screen, a cap that no longer sits securely and mesh obscured by deposits are different conditions. Ask what the provider observed and whether the passage below was checked. Substituting a piece of hardware cloth does not establish that the chimney will vent as intended.
Keep service access in the specification
Ask how the cap can be opened or removed for later inspection or sweeping and what part number will be recorded for the next visit. If the old cap has become distorted or there has been smoke spillage, keep the appliance off until the condition is evaluated.