Look at your 20D and see how beat up it is. That will tell you if you need one and if you have a belt or stuff on your side.
I just get a 10 pack of PDA protectors and sharp knife. If you get a bubble or fingerprint, you can toss it.
2000 740i-Annalisa and 2008 335i-Weebl. Weebl may wobble but has DTC
2012 X5d in Sparkling Bronze ( The Ultimate Cat Carrying Machine)