In general, Helium Hotspots ship with RP-SMA connectors.
However, if you purchased one of the first 700 Helium Hotspots, it shipped with a regular SMA connector.
If you want to upgrade your antenna, double-check your configuration (use the example pictures below), to make the decision for which connectors to buy.
Read more on differences between SMA and RP-SMA: https://oscarliang.com/difference-sma-rpsma----connector-antenna-fpv-copter/
These were posted in Helium Community Slack, and show the differences:
This is a representation of RP-SMA:
This is a representation of regular SMA: