These are spacers which enable 20 mm webbing to be used in the Weblocks Lynx 5 from Aki Slacklines.

There is one version with a clip, which attaches the spacers more securely to the sideplates of the Weblock. This is the version which I would recommend. The clip needs support material. The version with the clip should be rotated for printing, so the clip faces upwards.

For one weblock you'll need two spacers, where one of it has to be mirrored. This can be done easily in the slicer.