The difference between this series and B2/F1 is as follows:
F1 - more general ledgers; lists parts and equipment ordered for a job and describes the work done on site, repairing, fitting etc.
F2 - lists only castings made and foundry work completed to order, with credit to a customer paid for faulty goods noted in red.
Where an entry in a volume starts, for example, "from folio 49", this refers to the page in the volume preceding in date sequence. Where an entry ends "forward Monthly Ledger 207", this refers to the page in the volume immediately following in date sequence. There are obviously some earlier volumes missing, as B2/F2/1 refers back to a book not in the archive.
See also volume B2/F1/6 which contains details of accounts forwarded to Monthly Ledger volumes, although probably the missing earlier ones.