I do not like the "+" without text explaining what it means... Whenever I've used a + sign I will state exactly what I am trying to convey; 4 to 6+ most areas will be in the 4 to 6 inch range but there could be a couple of small pockets that reach 6 to 7 inch range. I rarely do it, but if I do, I always explain it... 4 to 6+ may allow folks to think you are thinking 10 inches...