This is an expansion card that adds an MC68882 FPU to your Macintosh Classic II. It's been designed to be as low-cost as possible.
Like the other FPU card available it offers a switchable clock source between the system clock (16 MHz, synchronous operation) and a crystal oscillator on the board - but does not use the incredibly expensive TE Connectivity AMP Connector (13€/14$ at Digikey) but uses a simple 90° Pin-Header connector (<1€) which can be ordered nearly everywehere. Still, it fits perfectly:
Also, it gives you the possibility to use 3 types of oscillators so you can use, whatever is in your drawer:
- SMD solder pads (SM77H)
- DIP 14 and
- DIP 8 pads