250ul Plastic Insert with mandrel interior and polymer feet,suits for ND9 Vials : IA250: 31*5mm: 100PCS/PK: 250ul Micro-Insert,31*5mm,clear glass,flat bottom; suits for ND8 Vials 250ul Micro-Insert:250ul Micro-Insert,31*5mm,clear glass,flat bottom; suits for ND8 Vials: IB300: 31*6mm: 100PCS/PK: 300ul Micro-Insert,31*6mm,clear glass,flat bottom; suits for ND9 Vials