Feb 19, 2019 · Help. Category:Fitbit. From Wikimedia Commons, the free media repository. Jump to navigation Jump to search ... Fitbit Charge HR (1 C, 3 F) F Fitbit Flex (2 F) S Mar 27, 2017 · Oh, and like every other Fitbit, the Alta HR is water-resistant enough to withstand rain, sweat and light splashes, but the company cautions against taking it in underwater or in the shower. The replacement straps for Fitbit Alta/Alta HR can effectively prevent your Fitbit Alta/ Fitbit Alta HR from falling-off Wrist Size: Small for 5.5"-6.7" wrist, Large for 6.7"-8.1" wrist. The replacement straps for Fitbit Alta HR can be adjusted according to your wrist circumstance; fits for Men, Women, Boys, Girls, and almost everyone.