FluxOptic sleeve remover

Surplus Shed sells an interesting adjustable water-filled lens called a FluxOptic. fluxoptic.com The inner sleeve can be hard to turn if you should crank it down too hard, and there's nothing to grip it with. This model will fit down in it and grab it a little bit, enough to unscrew it.  Very few people need this, and if you happen to have a FluxOptic you can avoid needing it by being careful not to overtighten.