How wide is the umbrella when opened?
37 1/2 inches

What's the guarantee?
Pretty simple: 10 years on the umbrella and 5 years on the messenger bag. If there's a material defect during this time we'll replace it for free or refund the product's price. 

Is this battery powered?
No. The patented design uses reflective fabric (Patent D872,989). You'll never need to replace batteries.