Burnable sulfur discs are necessary for preserving your barrels. Use the sulfur burner linked below and burn a 5g disc in each barrel each month to help keep bugs at bay. Don't forget to download and print the MSDS under the "Related Documents" heading.

10g discs are for 600 liter (160 gallons) barrels and puncheons. 5g discs are for 220 liter (60 gallons) barrels. Each miniature pail contains 1 kg worth of tabs.