California state law requirements for safety flags on oversize loads with certain dimensions has recently changed its standard.
Previously, state law required a 16-inch red or fluorescent orange flag on oversize loads (refer to CA Code under Chapter 2 commencing with section 35100). Now, an 18-inch red or fluorescent orange flag is required if the vehicle or equipment is being operated other than during darkness.
WCS Permits & Pilot Cars manufacturers and sells red and fluorescent orange flags via their online store, store.wcspermits.com.