Maybe this belongs in the folder on rules, but: 5.8.1.2 Standing Rigging/Permitted Alternatives/Jib luff groove systems other than that which is provided standard shall not have a fore-and-aft dimension exceeding 31 mm.
That would indicate limitation is size, which I cannot determine from any of the web info. Measure then check with class measurer before buying.
http://www.apsltd.com/Tree/d3000/e373.asp Harken Carbo H700112 $552
Tuff Luff SC170636EXT $339.20
Looking at their respective web sites Harken is .147 lbs/ft Tuff Luff .17 lbs/ft about 3/4 lb over approx 32'. BTW love that word on the Harken page--'lubricious'!
