What's the latest firmware for HTC ONe M8

Whats the latest firmware for the the htc one m8...

i have the tmobile htc one m8 on lollipop 5.0.2 with the following firmware 4.20.531.4

i want to know if i to change firmware to flash some custom roms...im soff with cid 1111111 and unlocked bootloader..

thanks