Round Lab Sunscreen

It is true, but still you should reapply sunscreen every 2-3 hours since sunscreens can go off of the skin with sweat a bit and the other thing is that you have no idea what's your med aka minimal erythema dose is, MED tells us how much you need UV radiation to see redness on the skin, such tests are done before uv treatments at hospital/PT but also when brands test uv before releasing it :)