If the setting calls for a classy yet killer look, you can rely on a black and white vertical striped double breasted blazer and a navy crew-neck t-shirt. Finishing off with a pair of brown leather flip flops is an effortless way to inject a more casual aesthetic into your getup. Naturally, you're looking at a good option for a baking hot summer day. This combo demonstrates that as a 40-year-old gent, you have a wide array of style options.