There are two designs that compress Silicone differently :
White GL base have more room for the silicone to flex for smooth operation. Good for overall setups.
Black GL base have better stability, but it will slightly add more tension. Good for low tension setups.
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Based on switch spacing, there are two options:
Fixed Spacing is traditional mounting method where all the switches have same distance/spacing. Good for user who prefer simplicity.
Variable Spacing, it allows user positioning switch individually, to adjust sensitivity for each directions. Good for user who like tuning lever. Switch Spacer needed to set the switches spacing (sold separately).
*All necessary screws are included on every GL base.
When adjusting the switches you don't need to unscrew completely, because the nut inside the base can be out of place and you will need to open the base to fix it. Just make 360 rotation counter clock to loose the screw until switches can move, then it is ready for adjustment.
When fixing the screw after adjustment never do overtight, it can damage the base and makes difficult to remove the screw, just put enough tension to keep the switch in place when actuate. Some tips, tighten it using thumb and pointing finger only when holding screwdriver to reduce overtighten risk.