It comes with integral elastic cord and suits a seat post range of 28.6mm-31.8mm diameter. The packer shown in the last photo is used for a 28.6mm seatpost.

Load capacity is 15lbs or 7kg and it measures 43cm from seat post centre line in length. The load area measures 21cm long by 10cm wide.

It has a handy threaded boss on the underside for attaching lights etc.

It weighs 419grams.

Nice bit of kit.

Thanks for looking!