The term “impact resistant” is defined as shutters, windows, and doors that have been proven to resist the impact from large windborne debris (defined by the test standards as a 9-pound 2×4 lumber missile striking end on at 34 mph). The strongest impact-resistant windows are capable of withstanding storm winds of up to 200 miles per hour. Other protective measures can include storm or hurricane shutters and wind-rated, impact-resistant garage doors. While impact-resistant windows and doors are more expensive, some insurance companies offer substantial premium discounts.