Ronstan Series 19, C-Track - Slide, Soft- Attached Ring, Plunger Stop rudder bearing they are not sealed units

they are not sealed units

Seal Carrier & Seal - Tawco

So a skeg that is a  12 - 150 - 4K is a 12 degree 150mm drop 4 bolt skeg

1 3/4" (45mm) Clearance for Ski Pole

Durable UV resistant polyethylene outers resist abrasion and withstand the effects of salt water

Ronstan Series 19, C-Track - Slide, Soft- Attached Ring, Plunger Stop rudder bearing they are not sealed unitsRonstan Series 19, C Track Slide, Soft Attached Ring, Plunger Stop Features: Spring loaded plunger stops allow fast, positive positioning of track slides Slides are available with swivelling cleat and fairlead to suit different crewing positions RopeGlide ring has a 'soft' attachment which allows up to 250 rotation Applications: Dinghy and small catamaran jib sheet leads Dinghy outhauls