The bag is well made and the fabric is thick enough, but could be a bit thicker. For storage in your backpack, it is well suited, but for more protection then you have probably more from giving. The size M is already very large, so that even my Sigma 70-300mm loosely fits in. For fixed focal lengths or smaller standard zoom lens (eg Canon 18-55mm f / 3.5-5.6) you should take one size smaller.