The Council of Vapor Xion 240w Box Mod which features a power boost button.

This pretty much allows the user to lets say set the power boost to 50% in the settings and if the user is vaping at 40w they can add the power boost whenever they like. The larger button delivers 40w power but if you hold the smaller button mid-vape it boosts the power up to 60w and then letting go of the smaller button reverts the power back to its initial 40w.