The externally adjustable cartridge is even more convenient than the internally adjustable cartridge. Here, you don't have to remove the cartridge to adjust the flow.
Figure 7 shows a photograph of a valve with an externally adjustable cartridge.

Figure 7. EXTERNALLY ADJUSTABLE FLOWCON SH VALVE WITH KEY

To change the flow, the key, on top, is rotated until the 2 digit numeric display corresponds to the desired flow. The numeric display (setting) vs. flow rate chart is provided by FlowCon. The key is removable after setting the flow to make the valve setting temper proof.