RBS or Sabre may have the batten caps. Would be surprised if Calvert did not. That style is similar to what windsurfers use. A good windsurfer sail should have them.

My most recent set of my sails used that style. Very easy to tension.

3 of 4 of my cat sails have leach lines. Hobie has had them on sails for years. Nice to have that adjustment as sails age and stretch.

Sail fast, Tom G