Letter Height	Distance for Best Impact	Maximum Readable Distance
3"	30'	100'
4"	40'	150'
6"	60'	200'
8"	80'	350'
9"	90'	400'
10"	100'	450'
12"	120'	525'
15"	150'	630'
18"	180'	750'
24"	240"	1000'