What type of toys will you introduce to a going to 4 mth old infant?

Hi! My bb is 7mo now but at that time I let her play with activity gym, frm fisher price. Keeps her active n also builds motor skills. Mine has a piano so she can kick n it will produce music whenever she does tt. Very interactive to music as well! For simple ones, I have cat rattle frm ikea very cheap. N also some teething toys n light toys with bells:) I think they enjoy it when there's sounds coming out when they hold or shake it. Hope tis helps!