You may notice that some of your flow cells have different colours, as shown in the image below.

This is expected. As part of our manufacturing scale-up process and to ensure continuity of supply, we have partnered with more than one supplier for core components in our flow cells. One of these components is visible through the window of PromethION Flow Cells. This may cause a colour difference between flow cells, with some being pale yellow and some orange. We have performed extensive validation and demonstrated that flow cells with different colours have equivalent sequencing output, pore counts and accuracy.