The magnets are strong enough to hold onto a vertical body panel even in high winds. The housing is solid enough that I wouldn't worry if I accidentally dropped one on the asphalt.
I tested these during a rainy night on a dark shoulder. They are visible from at least a half-mile away. Deployment is instant—just slap them on the car and you're set.
This kit provides incredible peace of mind. The LEDs are blindingly bright and the different flash patterns are highly effective for alerting traffic from a distance.
The lighting is excellent and the modes are useful. On rougher, vibrating surfaces they shift a tiny bit, but on a stationary hood or roof, they work exactly as intended.
I tested these at night and the reflective quality is staggering—they really stand out from a distance. It's a massive confidence booster when you're working near the road.