There is another Ingersoll which is part of Redipoint. It is Ingersoll St. Paul. I find this twist to be quite clever. use a standard sac, attach the “sac grabber” and insert into the tube to lock it down. That end tube ends in a knurled button that extends through a hole in the end of the barrel to allow the user to twist the sac. No special sac. No special restoration techniques needed.