im curious for owner that stay at high floor let say floor 18 or above did all ur window install grill?
we just bought a unit at floor 20 and we plan not to install grill for balcony slide window and master room window since they are facing outside, is that safe? any ppl encounter or heard of breaking in through those area?

It is also for your own safety. Unless you don't plan to open the windows or doors.

other area like yard, main door and those room window facing inside we will install grill. just those facing outside...cause it doesnt look nice
but we still planning the layout.

Pink the horizontal bars type of grill. It looks nice and modern. Don't go for vertical bars or fanciful designs.

if no kids then should be ok, since the view outside is nicer without the grill

what about invisible grill? has anyone tried?
www.invisiblegrille.com

Only suitable for condo IMO, landed not so much.