Girard-Perregaux is a prestigious Swiss watch manufacture with its origins dating back to 1791. Most of the time, Girard-Perregaux designs, develops and manufacture its own movements, and cases. In 1965, Girard-Perregaux designed the first mechanic movement beating at high frequency of 36,000 vibrations/hour. This is the Gyromatic HF.
Here is a GP from that golden era of late 1960's and early 70's. This is a day-date GP Gyromatic HF in black dial. It has three very ordinary looking silver hands and silver match-stick like hour markers. There is a GP logo embossing just underneath the 12 o'clock mark.
The case is a smaller and tiny turtle shell design with 36mm in diameter. Like most of the watches from the era, this watch has the acrylic top.
The crown is signed with GP.
This watch has the day and date function on 3 o'clock position.
The screw-in case back is flat and without any marking. This makes the watch very smooth and comfortable to wear.
On the inner part of the case back, there is a Girard Perregaux's seal or crest to certified the case is indeed an authentic GP artifact.
The center of attraction for this watch is this unremarkable looking mechanism. This is the 17 jewels unadjusted Gyromatic HF calibre 444-428 movement that beats at the highest frequency of 36,000 bph.