The McKesson cotton Unna boot contains a coating of zinc oxide and calamine to soothe skin and address topical issues. It's well suited for managing extremities with developments such as venous ulcers that require protection and support. The gauze bandage roll contains a non-hardening paste of zinc oxide that allows the bandage to stay moist, and calamine to help alleviate itching. A durable and non-raveling thread-locked gauze construction helps avoid the problem of loose threads entering wounds. Each zinc oxide wrap comes packaged in a vacuum-sealed pouch to maintain moisture prior to use. It contains no preservatives.