Hi im just wondering how often do you change your masks lens for safety reasons i have had my mask for about 2 years and used it probably 8 times i bought it second hand and its a bit scratched up but there are no cracks, personally i think i would just use a lens until its so scratched up that it looks really bad or if it has any cracks or other damage but i bought my mask for about £11 and a replacement lens would cost more than the mask so i probably wont bother replacing it if it does break i will probably just upgrade, my current mask is a vents avatar but if it broke i would probably get a I4 and or maybe a second hand cheap lens.