3/1a and b are standard fitch lock and keep. Now manufactured by Cavendish (catch now aluminium, satin anodised, replaces, cast SC plated version).
3/2 are pressed steel keeps to cater for various frame sections.
3/3 are Smith Wallis aluminium catches; cylinder lock and non-lock.
3/4 now discontinued; however can be re-run for large quantities (*please enquire)
Price (per item): £POA