Leckey Everyday Activity Seat Manuel D'utilisation page 17

8.1 Backrest cushion
The backrest cushion can be attached by
simply setting it onto the backrest, then
pressing down to locate the snap fasteners
at the top. Secure it to the Velcro on
the backrest and loop the elastic over
the hook. To fit the backrest cushions that
have 4 tabs, to a seatshell which only has 2
poppers, the SP-1842 retrofit kit is needed.