The pros of using a sealant are that it can prevent moisture and corrosion from affecting the lights. It can also help to prolong the life of the lights. The con is that it may take some time for the sealant to dry completely. If the sealant is not applied correctly, it may also cause the lights to stop working. Always consult the sealant manufacturer's instructions before using a sealant. Remember to always consult the sealant manufacturer's instructions before using a sealant.