Flex is a range of high quality sealants for use within industry for more exacting applications. They perform better at high temperatures and seal against oils and most chemicals.
Flex is supplied in a standard sealant cartridge and also a new PowerPack. A PowerPack is the easiest way to apply flex, especially for applications in a limited space where a cartridge gun is awkward to use. PowerPacks are also very clean to use as the sealant stops running immediately after the trigger is released unlike cartridges.