Above: ADM Slow Motion Control Knob Set. They have a 3/32 Allen key holding them onto the spigot. These are manufactured in the US so I figured they wouldn't be metric lol. Luckily I also have non-metric tools. I originally bought these for my EQ5 as the bundled Synta slo mo knobs (below) just aren't cutting the mustard. The stock Synta knobs, apart from being a bit rubbish, are plastic or resin and have a push fit. In my experience they perpetually fall off their respective spigots. The ADM knobs are aluminium and are fixed to the spigot with a hex/Allen screw/key. Then I had a brainwave! Vixen slo knobs are as bad the Synta ones. So I tried ADM's on a Porta II. The flexible Vixen cables also fall off a lot in my experience. So now I'm a really happy bunny as I can put the ADM knobs on the Vixen mount. Most excellent.