Stihl EDT9 tach comparing to the EDT8. First off it's a little smaller and has a function button I haven't played with yet. The EDT8 has a refresh of 1.5 sec. I don't have the specs on the EDT9 yet but it is faster. If anyone has any questions about it I'll try and answer or find out. I know everyone like videos as much as me so here a MS251 and a FS90 using both Tach's