Size: such as "6mm(50)", means: the filter Diameter is 6mm, Mesh Count is 50, you can view it in the picture description.
Number of Items: there is "1" and "10" for you choose. If you choose "1", we will send you 1pcs filter. If you choose "10", we will send you 10pcs filter.
Mesh Count is the quantity of the hole in 1 inch. Such as: if mesh count is 2, then the hole size will be 1/2inch, equal to 12.7mm, Approximately equal to 12.5mm. The larger the mesh count, the smaller the mesh hole size.