Flip Flop shows that in different lights any color is right. Flip Flop reacts actively with fluorescent and CFL lights. When in the sunshine it is a bright yellow and under CFL lights it turns a reddish pink. Flip Flop combined with using Boro Batch Watermelon will really make a reaction under any kind of light! Boro Batch Thins range from approximately 3.5mm - 5mm in diameter.