Need suggestion

[Le_Mow]

Hello I am planning to make a keyboard in future and I am planning to buy this PCB
https://kprepublic.com/products/hot-swappable-xd87-hs-xd87-custom-mechanical-keyboard-kit80-supports-tkg-tools-support-underglow-rgb-pcb-programmed-gh80-kle?variant=14736539320364
And I will buy Cherry MX Red Switches
And I am confused about Stabilizers...
What is 6.25u, 2u and 7u? As far I know these are the stabilizer lengths and the PCB that I show is 80 Percent which one I should buy?

[suicidal_orange]

Stabilizers are sold in 2u (double the width of a normal letter key) which is used for backspace, shift(s) and all shapes of enter, and 6.25u and 7u (6.25 and 7 times as long as a standard key) for spacebars.  There are pictures of boards with both on the page but the PCB looks to have 4 keys between the spacebar and arrows.  If this is true it uses a 6.25u

[Le_Mow]

Stabilizers are sold in 2u (double the width of a normal letter key) which is used for backspace, shift(s) and all shapes of enter, and 6.25u and 7u (6.25 and 7 times as long as a standard key) for spacebars.  There are pictures of boards with both on the page but the PCB looks to have 4 keys between the spacebar and arrows.  If this is true it uses a 6.25u

Thank you so much! Have a good day