This is a "snap in" guide to allow the use of flexible filament (Ninjaflex, Filaflex, etc..) with the CraftUnique Craftbot. This unit fills the gap between the top of the thermal tube and the feed/idler wheels. That constrains the filament so that it has less of an opportunity to buckle and deform during the extrusion process. It mimics the filament guide used on other printers such as the Makerbot R2X.I have printed this in PLA @ 200 microns on the Craftbot and in ABS (adjusted for thermal shrink) @ 178 microns on my MBI R2X. Both with 25% infill, 3 shells. The details was a bit better in PLA, but the ABS will probably give better long term durability. I "clean up" the bore with a 2mm drill. Remove the filament, fan, and left bracket screw on the CB. The guide should "snap" onto the thermal tube. It fits perfectly on my machine but I don't know how the assembly variances are on the CB. The drive wheel set screw may interfere with the guide. You can either relieve the guide to provide clearance, or remove the set screw and grind down the non-socket end by ~1mm. I didn't want to relieve the guide model for this clearance since I was concerned about printing integrity. Check for interferences after installing and make sure your drive and idler wheels rotate freely. Running a PLA print through the unit will help to "burnish" the bore and prepare it for your flexible filament.