Your can easily shorten a ski pole, but to make it longer is trickier.  We were asked by Magnar Dalen - famous ski trainer - to develope a kit that could add a little to a too short pole.  - One day I realized that we did have the materials and the means to actually do what was asked for.  The first attempts were not simple and they were not sturdy enough - but that's the way we live in R&D.  The ball was set in motion and after a handful of failings we have now a simple strong kit for lengthening just about any ski pole - round or Triac.  We have lengthened poles from 1 och 15 cm.  And customers are satisfied and some return for more - that's an accolade.
The ski pole lengthener we will keep in stock is 8 and 10 cm and available for round carbon fibre poles and Triac poles
On demand we will make lengtheners up to 15 cm.
If you want to lengthen an ordinary "ski-pole" or a dampended "roller ski-pole" makes no difference - it's easy.  Instructions are included with all the special glues and accessories necessary.

Picture below shows one 8 cm elongator for round pole, one 10 cm elongator for round pole and one elongator 8 cm for Triac pole.  The kit includes abrasive paper and 1 yellow stick of hot melt glue for enlongation of winter skiing poles.  For roller ski poles we include one stick of grey hot melt glue and som carbon fiber chips for the assembly.