PPI, which refers to the number of holes per inch, is a unit for measuring the density of holes in a sponge.A high PPI means that the pores in the silicone sponge are denser.
The 40ppi silicone sponge has a larger pore size (lower pore density), better air permeability (increased air volume by 30% to 50%), and is easy to clean. It is suitable for scenarios that require high air permeability or frequent cleaning, such as air filtration systems.
The 60ppi sponge, due to its dense pores (with a 50% increase in pore density), performs more prominently in terms of sound insulation (noise reduction of 8-12dB) and thermal insulation (thermal resistance increased by 20%-35%), making it suitable for acoustic engineering or heat insulation applications.