GDR 3 os version

[raxy21]

Hi, i have a Lumia 720 with me with gdr3 with Lumia black update, what is your os version for it, my phone is showing- 8.0.10517.150.
once i checked any updates for my phone it is showing new update available with Microsoft update 8.0.10521.155 with this version, is it any security update or anything anyone can confirm your os version?
I'm i running older version help me?

 

[Chris_Germany]

Don't know just install the update and fine?!
Did you try and google the firmware number? Sometimes google gives you answers....

 

[Angel Fernandez1]

Don't know just install the update and fine?!
Did you try and google the firmware number? Sometimes google gives you answers....

Sometimes Bing does too

 

[raxy21]

Thank you ill try it once.