SummaryThis is compatible with all frames with 5mmx50mm (top bar of the frame). I needed a spool holder to hold the filament in for my Sintron prusa i3, so I decided to get the original one for Prusa i3 mk2, designed by Josef Prusa, from Prusa Research and modify it to fit the Sintron acrylic frame, by extending the frame mount from 4 to 5cm and adding a 8mm threaded rod to hold the spool and give it more security and space for two 1kg spools. If you want the simple ones without the 8mm threaded rod see here: Spool Holder for Sintron Prusa i3Print SettingsPrinter Brand: RepRapPrinter: Prusa i3Rafts: NoSupports: NoResolution: 0.2Infill: 15% minimum recommendedNotes: Wall Thickness: 3layers (top, bottom and sides) minimum Post-PrintingWhen inserting the 8mm rod in the left holder, the rod will be really tight and will need to be screwed in. I have done this to make the rod stable and because the right side is the one with a lose fitting to remove and insert the spools. Just unscrew the right holder, insert spool and screw the holder again.