|
US Std. #4 and coarser …… . . . . .
US Std. #5 to US Std. #18 …… . . .
US Std. #20 to US Std. #50 …… . .
US Std. #60 to US Std. #120 …… .
US Std. #140 to US Std. #200 ……
US Std. #230 to US Std. #325 ……
US Std. #400 to US Std. #635 …… |
100 uses or every 40 months
75 uses or every 30 months
60 uses or every 24 months
50 uses or every 18 months
40 uses or every 12 months
30 uses or every 9 months
20 uses or every 6 months |