Dual blades apart:
Clear away frost twice as fast! The two brass blades clear more surface area when used in a back and forth motion. A single pass over the glass is like two passes in effect, so you’re clearing more frost without actually doing more work. The two blades pivot when in this position, so so the optimum scraping angle is always maintained even if you're reaching across a windshield. There is built-in flexibility in the blades so even on a curved windshield you get the scraping action of the full blade.