Typically adjustable shock absorbers just have an integral plastic knob or sometimes a screwdriver slot to adjust, the former shown below on left hand Spax coil over shock.

I wonder if you are referring to adjustable platform coil springs though also as below and which do require a C spanner?

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If you find one to accomodate collar diameter the lug of usual flat plate C spanner should fit it in adjusting hole as above. These ones have a hex grub screw to lock collar into place, others have two thin collars to lock adjustment against each other and require two C spanners.


Richard

2018 Roadster 3.7
1966 Land Rover S2a 88
2024 Royal Enfield Guerrilla 450
1945 Guzzi Airone