Use PulsaBath wet or dry. Its soft, porous spongy texture absorbs soap or lotion making it glide softly on the skin. PulsaBath Vibrating Bath sponge is completely waterproof so use it freely in the bath, shower or hot tub. Its vibrating massage action will invigorate yet relax tired muscles. The diameter is 4¼" and uses 2 AA size batteries, not included. For a thrilling encounter, use it on your lover!