You are unlikely to sell a shock without specifying it's dimensions. 150 mm of travel is not a shock specification, but rather a frame specification. Shocks are described by their eye-to-eye length and their stroke.
Eye-to-eye can be measured directly with a ruler. It's usually measured in inches. Stroke is basically equal to (eye-to eye uncompressed) minus (eye-to-eye fully compressed).
Stroke can also be approximated by reading what is written on your spring. For Fox shocks you can often round the number written on the spring down to the nearest quarter of an inch to obtain the stroke of the shock.

 Usually people just look up their shock dimensions online, but I guess for your frame it is hard to find.

 Sorry its e2e is 8.75