Blasting Area Switch Off Radio and Mobile Phones (T4-7)The Blasting Area Switch Off Radio and Mobile Phones (T4 7) sign is used to warn motorists and workers entering a blasting zone to immediately switch off radios, mobile phones, and any electronic devices that could trigger explosives. This safety critical sign is essential for mining, quarrying, and construction environments where controlled blasting operations are taking place. Manufactured from red CL400 Class 1W reflective material, the T4 7