I would like to install window grille. Any recommendation? Ok with typical ones

Standard aluminium grills are better than invisible grill as invisible grill will eventually loosen and become a threat. This is mentioned by one of the window vendor we spoke to. They say the wire on the invisible grill will loose and as kids grow up, they will tend to pull the wires which is dangerous. Also in case of emergency where window is the only way out of the house, then standard grills can atleast unlock unlike invisible grill. For the price depends on your window size. Will range from $900-$1400.

Here is the contact I have when I did renovations for my BTO last year. Engaged him based on recommendations from my neighbours. I only put up grilles for my service yard then. His work is good and his pricing is reasonable. You can try contacting him if you are interested. Jia Le Aluminium Mr Koh Thiam Hock 97466305

U can ask for a quote from him. Mr Ang 9850 9646