Both the Wind Sign and Flex Frame Springer are great for outdoor sidewalk signs. Here are a few differences: WEIGHT: Wind Sign: 26 lbs. Flex Frame: 20 lbs. One of the key differences between the two is that the Flex Frame does not require ballasting and can withstand up to 60mph winds as is. The Wind Sign would require 115lbs of dry sand ballasting to be added to allow it to withstand 60mph winds.