This is a set of two matching Mercury 65mm spools.  They can be inserted directly into standard 70mm metal cassettes.  A pair of these come free with every Mercury back available on this site.  If you wish to use your own back or purchase extras, this is the item! Note that these accept Kodak's original metal retaining rings, but do not come with them.  Use blue painter's tape to thoroughly fasten 65mm film to these spools when loading, even if using a metal retaining clip. We have several variants, to cover all 70mm backs: Centered: These spools perfectly center the 65mm film.  They are for use with all Mercury modified backs (medium format or large format) sold on this site, as well as original Graflex RH-50, Linhof Cine Rollex backs, and Mamiya 70mm backs.   Offset:  These are like those above except that they offset the 65mm film slightly to enable it to make contact with the spacing wheel on Hasselblad A70 backs. Max Offset:  70mm backs for 645 cameras (Bronica ETR and Pentax 645) require 65mm film to be pushed fully to the side of the roller, which is variant accomplishes. Transet:  These are special spools designed to fit in a Beattie Coleman Transet 70mm back, as "drop-in" replacements for the standard 70mm spools.  Note that these do not fit inside a 70mm cassette; the Transet back isn't designed to accept those. 120:  These special spools accept 120 film.  You will need, in the dark, to roll the film off of its original 120 spool and then back onto one of these.  These spools are then inserted into standard 70mm cassettes and operate as usual, but with 120 film (with or without the backing paper).  These also accept 220 film.  These work only with Mercury-modified RB67 70mm backs.  They can be used experimentally with standard non-Mercury RB67 backs, but are not guaranteed to produce the correct frame spacing.  Note that 120 film can also be shot in the Mercury 6x12 Panoramic back via our 6x12 120 Adapter Kit; these spools aren't needed for that method.