Summary This design is largely based on the original slider block of Ultimaker 2 (first edition September 2013). What's different or better? This is not a pure 1:1 copy, but a variant newly created. with the essential features and dimensions from the original! This design is not optimized for injection molding, but for 3D-Print. All snap locks can be opened more easily, so that maintenance work can be performed easily and reliably. When you create a small supply as a precaution, you need not wait for expensive original parts, or cheap China Goods. Universal use: It is a more universal version available for tension springs with different inner diameter. Then you may need to drill out the leadthroughs, and use a screw. A bolt with nut thus secures the half-shells and keeps the tension spring in position. !!! Choose the screw to match the inner diameter of the tension spring !!! Good for MXL- and GT2-Belts with a maximum width of 6.5mm. Suitable for sliding bearings with the following dimensions: 8mm x 11mm x 30mm. The bearing seat is: 8.5mm x 11.2mm x 30.2mm. 2018-04-14-NEW: Suitable for sliding bearings with the following dimensions: 8mm x 12mm x 30mm. The bearing seat is: 8.5mm x 12.2mm x 30.2mm.