The 3 x 5 size is nice for giveaways with your business card inside. They are a little wider than our biz card size bags but are the same height (length). They are self-sealing. The 4 x 9 size bag is perfect for larger samples, small hostess gifts, giveaways, small gift with purchase & more. These bags have triangular sides (gusseted) so they will expand to hold more contents. They will sit flat if you have items inside that are weighted or will sit up by themselves.Bags are also food safe. Bag background is clear. Our Satin Ribbon Thank You in Pink/Silver, Black/Silver or White/Silver makes a great combination.