The XpoBalance from Lastolite works in a similar way to the EzyBalance but has the added advantage of three different grey surfaces on one side and a black, white and 18% grey surface on the other side, collectively offering a range of white balance, exposure, colour correction and bracketing adjustment options.
On the grey side with XpoBalance you get normal 18% with +1 or -1 stop adjustments which makes batch adjustment much easier.
The unique focusing site is used as the focussing point for your White Light Balance. You then correct the exposure by making the XpoBalance the centre of the shot. The same can even be done post exposure (if preferred) by using Photoshop and creating an 'action' involving the grey/white or black dropper in Levels Adjustment to get to the correct exposure and colour balance.
This grey card is a major benefit when working under pressure at events such as weddings or fashion shows but is equally valuable for batch shots of products within the studio.