These are avaibale for both the Assist and Assist PLUS and are not cross compatible. whilst it wont hurt your battery or checker, the Assist PLUS checker wont display the correct information for an Assist battery, and vice versa.
In addition, these have been programmed to display Voltages. Simply single press the power button once plugged in and it will toggle the display. This is useful for tech heads, and can be used if we need to troubleshoot with you.