JPJ do have a gadget to measure the % of light penetration known as Visible Light Transmittance (VLT), and % of light deflected known as Visible Light Reflected (VLR).
Our JPJ ruling are minimum 70% VLT for front and rear windscreen, and 50% for side windows. Any less VLT, and u are liable for summons.
And you can ask them to show with the gadget the VLT of yr glasses..... but make damn sure that yr tinting is way above the legal limit.... else u get slapped with a summons and ticked off by them, coz u press them to prove u wrong ma.....
All tint shops claim their film is legal, which is true if measured by their film alone. But did they take into considerations of the natural tint prevailing in our original glass?? Did anyone bothered to ask them (the tint shops) to use the gadgets to prove the VLT after installation is within the JPJ ruling??? Guess not..... so take your own risk, irregardless of brand....