I have found that the HennTec track tension set is not designed to work with the HL metal idlers "with bearings". The HennTec bearing are smaller than the enlarged bearing opening in these wheels also the axle for the HennTec set is too small to work with axle opening in these bearing. The HennTec system is designed to fit the Heng Long plastic or metal wheel that has the "standard" brass sleeve bushing. So the Heng Long metal idlers without bearing are what is needed.

Barry