My dual channel scope came with those GTP-150A-2 which even if they are high quality probes, my complain is that the package was not including and spare tips.
A bit of further searching leaded me to PINTEK in Taiwan which is the original manufacturer.
PINTEK looks to enjoy the respect of many T&M companies which need quality products as probes and accessories.
The long story sort, there are available spares for the specific model, and it is distributed in Europe by a German company "PeakTech"
There is a offering of a set of parts which called as:
TK-KIT - Spare Part Kit for Oscilloscope Probes
And also are available just the tips as:
TK-TOP - Probe Tip for Oscilloscope Probes
Mr. Vito the Italian reseller of "PeakTech" has offered to assist me regarding getting two accessories KIT, plus extra tips.
KIT
http://www.peaktech.rce.it/index.php?main_page=product_info&cPath=79_83&products_id=333Tips
http://www.peaktech.rce.it/index.php?main_page=product_info&cPath=79_83&products_id=328I hope this info to help and others too.