I have been using this pole for months and I love it.
1] Drill out the rivets or cut the end off.
2]The inside diameter of the end section is exactly the same as the Unger no 2 section, so if you have an old Unger pole you can cut 6 inches off the end piece and it will fit into the Harris pole, if you don't have a piece of Unger, Jeff say's that they sell tube of the right diameter in B&Q.
3] Insert the 6 inch piece into the end of the Harris pole, drill and pop rivet in place
4] Get an Unger threaded cone and angle adapter
5] hold the cone or angle adapter next to the 6 inch inserted piece and note how far down the spring lugs on the adapter are, and mark the spot with a marker pen.
6] Drill through your mark using a 6mm drill bit.
Your pole will now take all standard Unger adapters.
It really is a dead simple job, and you end up with a very light, robust pole that's a delight to use. Dai