Actofit bands are built for the active lifestyle market; they're durable and IP67. These devices are resistant against water ingress to a maximum of 1 metre of water for up to 30 minutes, as well as protected against the dust ingress.
IP 67 is applicable only on fresh water. Devices aren't guaranteed to hold up to salt water or any other liquid. While showering with IP-rated devices isn't recommended, the device could break if you forget to take it off. The device could begin to leak and become damaged with continued exposure however, and water damage may not be covered under the warranty. Make sure the device is completely dry before charging it.