The 'Flexers' section is your pool of favorite workers who will have priority access to your shift and as a result they are more likely to claim and work your shifts. You can add Flexers to your pool of staff in two ways. Workers will be automatically added when you rate them 5* after a shift.
You can also add workers manually by going to your Profile screen. Select the 'Flexer' section, then tap 'Add Indeed Flex Staff'. You can browse and add workers, filtered by job roles. You can access your pool of favorite staff from the 'Flexer' option on your profile.
You can remove a worker from your pool of Indeed Flex workers by going into 'Flexer', searching for the worker you'd like to remove, selecting the worker and scrolling down to 'Remove worker from Indeed Flex staff'.