
Of course there are cheaper universal lens caps. But sometimes you want a perfect replacement for the original quality of a lost item. And if you bought the T3i (or 4 or 5) with a set of 18-55mm lenses, then that's it. Exactly. The main benefit of this lens cap over other (and cheaper) Canon lens cap latches you may see is that you attach it in the center rather than the outside, which is just easier and feels more secure. Not sure if this will fit: you need to know your lens's filter diameter, which is the inside measurement of the ring on the front of the lens. On the 18-55mm f/3.5-5.6 IS lens that comes with the T3i you can see "β58mm" which means 58mm filters and this lens cap will work. For example, if you bought a Canon with an 18-135mm lens set, it will show "β67mm" instead, meaning you need a different lens cap.

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