Bresser Immersion Oil 5 ml. Without this oil it's not possible to get a sharp image. Specifications for Bresser Immersion Oil: Manufacturer: Bresser Volume: 5 ml Features of Bresser Immersion Oil Immersion oil for 100x oil-objectives Refractive index (RI) nD=1.515 according to ISO 8036 Volume: 5 ml Package Contents: Bresser Immersion Oil Bresser 59-12300: Immersion Oil 5 ml