Bowden tube clip

Replace of the ´blue horse shoe´ that comes with the Ultimaker Kit.

This design takes the play out of the Bodwen tube, reducing retraction and underextrusion issues.

This version is a variation of the ´Ultimaker retraction ring´ made by JelleBoomstra, being smaller, wich allows to rotate it easily, making possible to attach it to the Hotend´s Bowden tube without problems because will not touch the cables (cartridge heater, PT 100, and fan).