Ronstan Track - Series 26 - Gate ronstan ball bearing utility blocks - series 20 - single swivel shackle head The 2 Boston valves have

The 2 Boston valves have different thread patterns

129470-42531

For 2" version

With a 2-inch diameter

Momentary on/neutral/momentary off positions

Ronstan Track - Series 26 - Gate ronstan ball bearing utility blocks - series 20 - single swivel shackle head The 2 Boston valves haveConvenient track mounting slugs are available for fitting standard profile track to the luff groove of existing masts. Patented system uses low profile cars running on twin races of acetal ball bearings. Cars use the existing luff groove of the mast (no track or installation work required). Ball bearings are captive for easy loading and unloading of cars from mast. They can be easily switched between fully battened and soft luff mainsails. Minimum