The TSpinEditEx control is found on the the LazControls tab of the Component Palette. It is useful for setting a numeric setting made on a form. TSpinEditEx is just like TSpinEdit in fact a combination of a TUpDown and an associated TEdit control.
The main difference with TSpinEdit is that the behaviour is consistent across widgetsets, and that it supports Int64 values.
TSpinEditEx has a bunch of added features: