roller slide
/ˈrəʊlə ˌslʌɪd/noun
1 Photography. A slide for rolling the sensitive paper or film from one spool to another by a fixed amount corresponding to the width of the image area. Now historical.
2A movable carriage or table that moves over a set of rollers; a mechanism holding such rollers.
Origin
Mid 19th century (in an earlier sense). From roller + slide.