Rack

A rack for holding assay tips, the rack comprising:

• a surface plate, the surface plate comprising assay tip through boreholes extending substantially in a Z direction orthogonal to the surface plate, the assay tip through boreholes having seating areas for receiving assay tips in the rack;
• a peripheral skirt extending from a periphery of the surface plate substantially in the Z direction;
• and
• at least four guiding elements extending substantially in the Z direction, a first pair of the four guiding elements being respectively arranged near opposing edges of a first side wall of the peripheral skirt and a second pair of the four guiding elements being respectively arranged near opposing edges of a second side wall of the peripheral skirt, substantially orthogonal to the first side wall,
• wherein each guiding element comprises a slit and a corresponding rail, the guiding elements arranged such that the rail of the rack is guided into a corresponding slit of a similar rack thereby aligning the rack and a similar rack and such that assay tips received in the assay tip through boreholes of the rack nest into the assay tips received in assay tip through boreholes of the similar rack when the racks are stacked.