Pipercross Induction Kit, replaces bottom half of existing air box. For a 1.8 16V engine,

At the heart of the Pipercross air filter is a specially developed polyurethane foam which acts as the filtration medium, having both higher performance and life expectancy than paper. Pipercross reticulated foam is created by a chemical reaction - it's placed in a gas filled combustion chamber where a controlled explosion burns away any complete cell walls in the material to form a strictly quality controlled skeletal cellular structure.

This process, ensures that the foam consists of tiny open cells which trap contaminants to protect your engine against even the harshest of environments without compromising air flow.