Abstract: In an embodiment, a fluid ejection device includes a substrate with a fluid slot, and a chamber layer over the substrate that defines a firing chamber and a fluidic channel extending through the firing chamber and in fluid communication with the slot at first and second ends. The device includes a tophat layer formed as a two-layer stack over the chamber layer, and a nozzle bore over the firing chamber that comprises a greater cavity formed in a first layer of the stack and a lesser cavity formed in a second layer of the stack, the greater cavity encompasses a larger volume than the lesser cavity.