I recently had to buy a new mask. It came down between the Eflex and the I4s. I went into the store preferring the Events because I had Avatars before and liked the lens system. However, the Eflex has a larger frame than the Avatar/Events but the duel layer of the thermal lens hadn't been extended. This left a huge black line around the outside of the lens...annoying. So I bought the I4s. I recently used them while it was raining in about 50*F temps with ZERO fogging. All in all, the I4s have been amazing for me so far.