Holy Panda switches are a Tactile switch with a very pronounced, short, but rounded tactile bump. The bump is at the top of the switch, meaning there is very little pre-travel before feeling the tactile feedback, the bump is smooth but moved over quite quickly.
Originally, Holy Panda switches needed to be built from the stem of a Halo Switch and the housing of an Invyr Panda switch, according to the original GeekHack thread only around 10,000 Panda switches were made. Their infamy started when Top Clack member Quakemz put a Halo stem into the Panda switch housing.
For a long time neither Halo switches (for the stems) or Panda switches (for the housing) were available easily, driving prices up to 6 USD per switch, this was partly because of the scarcity of Halo stems, but mainly because the original Panda moulds (tooling) were thought to be destroyed, preventing more from being created after the popularity spike.
Massdrop began selling Halo Switches again, meaning if a switch housing close to the Invyr Panda could be created, a switch equivalent to the Holy Panda could be built once again.
The GSUS ‘New Panda’ IC/GB started and seemingly filled this role, right at the cusp of the GSUS Groupbuy, Massdrop started their group buy for Pre-assembled Holy Panda switches, claiming to have the original Panda switch tooling, further claiming it was never destroyed only partially damaged. This caused quite the stir amongst the community, especially those in the GSUS Groupbuy, the community began to distrust Massdrops claims to have the original tooling. This prompted Massdrop to send samples of this switch to Quakemz, after a little bit more drama it was confirmed that the actual production samples were, in fact, Holy Panda switches.
Further drama added to the whole situation by problems in the GSUS Groupbuy caused the creation of yet another Panda switch alternative, the YOK line-up, a clone of the GSUS version.
The YOK switches were easily and widely available, fulfilling multiple buys before the Massdrop Holy Pandas had even cleared all the drama.
Force Curve Graph: https://plot.ly/~haata/377/top-clack-holy-panda/#/
Panda Switch Specs: https://mehkee.com/products/panda-switches?variant=3356848783388
Drop Holy Pandas: https://drop.com/buy/massdrop-x-invyr-holy-panda-mechanical-switches