The 25 micron size is the best choice for dry sift, bubble or other fine material.
Rosin Evolution bags is known for their quality & features:
Dimensions: 5,08 x 11,43 cm (2x4,5" inches)
Rosin Evolution bags are designed to withstand heat and pressure.
Each bag will hold 15-25 gr. and is turned inside out for maximum yield.
The 25 micron bag also has a custom seam specially designed to contain fine particles and prevent blowouts.