14.5" (368mm) Helios Solar Glass Filter. Fits Optical Tube Diameter 14 1/8" (358mm) to 14 3/8" (365mm)

we all know what the tape measure is it comes numbered in inches and in feet but one of the problems that most people face is they don't understand what all of these little hash marks are in between the numbers and that is what this video is about to help me explain I have created this drawing starting over on the left side we have 0 and finishing up over here on the right we have 1 inch from the inch we divide that in half and we have 1/2 inch so this hash mark right in the center is 1/2 inch then we divide the 1/2 inch into 2 and that creates 1/4 so we do it on both sides so we have a total of 4 quarters 1/4 2/4 3/4 for quarters for quarters equals 1 inch and then we divide the quarter by 2 so this hash line is 1/8 and we have 1 2 3 4 5 6 7 8 & 8 8 equals 1 inch now these little hash marks down here are sixteenth of an inch there are 16 16 7 8 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 an