The continuous evolution of new moisture-sensitive active pharmaceutical ingredients (APIs) has increased the popularity of roller compaction, prompting research into various processing parameters that could optimize roller compactor production. The Alexanderwerk WP120, equipped with an integrated two-stage mill for small/medium-scale batch manufacturing, is a notable roller compactor. This study aimed to assess the influence of the upper mesh size in the integrated mill of the Alexanderwerk WP120 roller compactor on granule Particle Size Distribution (PSD), flow, and compactability. The findings indicated that the upper mesh size could significantly impact the PSD of lower solid fraction ribbon/wafer (≤ 0.65SF). Nevertheless, these observed differences in PSD may not be substantial enough to induce significant alterations in bulk powder flow and compactability properties.