This insert fits into the seed metering mechanism of a grain drill to handle small, free-flowing seed such as rapeseed. It replaces the standard metering component to reduce the seed-cup volume, preventing over-metering and ensuring a consistent, low-rate delivery for fine seed. A worn or incorrect insert causes uneven seed distribution and skips in the row. The manufacturer machines this insert to the same internal profile as the original assembly, so the metering wheel rotates without binding and the shut-off slide seats correctly.