Will you need more than 1 speed light ?
The number of speed lights used depends on the situation, other equipment used (camera and settings, lens, speed light output, etc.), and photographers style/objective. This is a fairly efficient modifier with a sliver reflective surface and no light absorptive covering. As the typical shot for this sort if modifier is short distance one good quality speed light should do it. That being said, my preference is to use two or three speed lights at lower power because it is easier on the equipment to stress it less, with perhaps (very) slight improvement in uniformity since a single light cannot be placed in the center of the reflector. Basically I use several because I have them rather than out of necessity.