Silver Duplicating Films , there is a pdf file attached herebelow
Imagelink Pos Duplicating Microfilm (Estar Base)
Imagelink Pos Duplicating Microfilms are micro-fine grain, silver reverse image films used for making contact prints from camera microfilms and duplicate microfilms in microfiche and roll-film applications. Silver duplicating films have a life expectancy of 500 years (LE-500) when processed and stored properly.

Imagelink Direct Duplicating Microfilm (Estar Base), Direct Intermediate Microfilm 2470 (Estar Base)
Imagelink Direct Duplicating Microfilms are micro-fine grain, silver, direct-image films developed for making contact prints from camera microfilms and duplicate microfilms. Use Direct Duplicating film for your microfiche and roll-film applications; and 2470 for making intermediate direct-image contact prints. Silver duplicating films have a life expectancy of 500 years (LE-500) when processed and stored properly.

Nominal Thickness Data (mils)
•2470: 4.0 mils Estar base (4.2 mils total, unprocessed)
•IMAGELINK Pos Microfilm 10: 4.0 mils Estar base (4.2 mils total, unprocessed)
•IMAGELINK Direct Duplicating Microfilm 10: 4.0 mils (4.2 mils total, unprocessed)
•IMAGELINK Direct Duplicating Film 06: 2.5 mils Estar base (2.7 mils total,