The product utilizes US standard thread.

Very strong leather ,  for fine detailing finishes
Made of very high grade leather and aluminum
Set of 4
Small - PURPLE  3/8" 10 mm in diameter 3/4 " (20 mm) long  excellent knockdown and blending tip
Medium - RED  1/2" 13mm in diameter excellent knockdown and blending tip
Large - GREEN  3/4 " ( 20 mm) diameter  3/4" (20 mm ) long knockdown tip - for crown and medium repairs 
Extra large -GRAY 1" ( 24 mm ) knockdown tip for very large crown and large repairs - grate metal movement
Great for aluminum and steel panels
Fits most knockdowns and blending tips 
All  standard threads 5/16
The leather tips are very effective, but  they need special care
Always keep them clean
Do not use on sharp edges - leather can be easy scratch or damaged