The Nitecore page for this light is at https://flashlight.nitecore.com/product/p18, including the manual.
For me, particularly for a flashlight meant to be "tactical", details of the user interface are critically important. To summarize the UI from the manual, the tail switch turns it on and off in the last mode used. While on, half press the tail switch to cycle through ultralow - low - medium - high - turbo. "Half press and hold" to access turbo when the light is on. "Full press and hold" from off starts with the memorized mode and then goes to turbo. Direct access to ultralow is available using the tail switch and the side switch simultaneously. A full long press of the tail switch from accesses disco modes.
This is a good price (Amazon is $20 higher in the US), and my experience with Nitecore has been very positive. But I don't care for the UI compared to (for example) a Surefire Stiletto with a momentary tail switch for maximum and a side switch that always starts in low mode (when so configured). Other examples come from the variety of Klarus lights with a main switch and paddle on the tail which allow for momentary or switched-on access to maximum and lowest modes with a single press (when so configured).
On the other hand, the P18 has a lot more output than the Stiletto and carries bezel down, which I strongly prefer.
For me, I'll pass on this one due to the UI.