Grade X for the Walker Filtration Walker A Series - Old line is the intermediate-stage general-purpose coalescer in a typical compressed-air filtration train, and works to deliver finer coalescing of residual water and oil aerosol downstream of a Grade P pre-filter and ahead of the fine-stage polishing elements. The Ultramax Systems Grade X element is built to match the Walker Filtration OEM specification on dimensional fit and filtration outcome, so it slots straight into the genuine Walker Filtration housing with no modification. A like-for-like, Australian-stocked replacement at a meaningful saving against the genuine Walker Filtration part, with comparable service life and air-quality outcomes.