Yes , I to love helical focusers . I have one on my 10 inch f/10 Newt ( in storage in NZ sadly ) and because they are such a low profile ( 30mm ) it allows me to have an only 'One inch ! ' secondary mirror , great planetary scope that one.
Its the 2 piece alliminium tube sections on the Dobbo mount in this photo .
Mine is an Antaries made one , very well made and super smooth..
Brian .