The original test image was created at 3000 x 3000 pixels. The different circles show the design/bleed area for different products. Notice how poorly the image fits some products. If you wanted to create one image to fit the most products, without any resizing, you would create one where the important part of the design is within the pink (center) circle and the background was white or transparent. This image has concentric circles to show the various fits on the round items. Be careful, however, of using a round border as the image isn't always perfectly centered. When that happens the border will not fit correctly. Making the background transparent will eliminate the white square on the dark apparel. For ideas on using the fewest number of images to fit the most products check the image efficiency article.