Our red pH probes, H-Rubies, have struck again! H-Ruby-conjugated dextran, in combination with AF488, enabled the measurement of vascular pH variations using in vivo two-photon microscopy. These results have now been published in Nature Communications. Congratulations to Sonia Pfister for her great contribution, and a big thank you to Serge Charpak (Institut de la Vision, Paris, Inserm) and his team, especially Marine Tournissac.