going to build a rod useing micro guides  bmkog-4   did not buy a tip top guide  i dont know what  size to buy  any of you guys  know what to use   going to build a conventional  rod  not a spiral 6'-6"  med-fast tip  baitcasting rod

check with the manufacturer of the blank . that measurement is always given as is the butt dia. or you can get a tiptop gauge http://www.acidrod.com/tools_measuring.html

also , here is a chart

Tip tops are sized by Ring/Tube.  Fuji BMCAT is a 4.5 ring and available in sizes 4-6. The tube size is measured in 64ths of an inch. As stated, the manufacturer can give you a size or you can put a micrometer on it. If you have a Mud Hole catalog, they have a chart that you can lay the tip on to size it. If you go with the listed spec, you might want to also order 1 size larger and smaller due to slight variances in the manufacturing.

i sure do thank you guys  kb