spinaker pole!

Im hoping someone can point me in the right direction. I can’t find any information on these plastic threaded sleeves that lock the pole sections in place. Both of mine have cracked and I'm looking to replace them. There are no markings on the pole either which adds to the mystery. Thanks everyone!

Would anyone have or know where i can find a spinnaker pole sliding car for the isomat NG105 mast. I got onto Rigrite but they want $350 plus $100 freight for this car which seems CRAZY! Wondered if maybe someone had one in a shed or drawer- i m the eternal optimist!