The phrase "are only usable" is correct and usable in written English.
It can be used to indicate that something can be used, but only in a limited or specific context.
Example: "These tools are only usable in the designated areas of the workshop."
Alternatives: "can only be used" or "are solely applicable".
In addition to current vintage allowances, which can be used this year or in the future, the program also offers a smaller amount of future vintage allowances, which are only usable in the next compliance period.
Ground control would provide valuable data on the former development of cultivation on upland areas which now have thin upland soils which are only usable as pasture (eg Titrish area, Turkey).
Our goal is to develop an accurate and fast algorithm that does not make use of extensive fitting to obtain good predictions, as this often leads to results which are only usable for the investigated building.
Korean government regulations, which were developed in the wake of a 1990s decision by the United States to ban the export of 128-bit encryption protocols, require the use of these controls, which are only usable on Internet Explorer.
Movie rental is obviously a model that most consumers are comfortable with, but it will be interesting to see whether downloading media files to our computers that are only usable for a short period of time makes sense to people.
Obviously outdoor workspaces are more feasible in temperate climates, but can still be exciting (or possibly even more so to us Midwesterners) in areas where they are only usable in certain seasons.
It would feature "an encrypted reference file" that is "only usable in conjunction with the proprietary algorithm software of the system," the letter explained, in a predictably failed effort to mitigate concerns about privacy.
So the question is, how do you design so it doesn't look like it is for or is only usable by someone with a specialized need?" Richard C. Duncan, the senior project manager for the Center for Universal Design, said: "Most people think U.D. is a term that is synonym with accessible design.
Originally, the design called for more than four I/O ports on our CPU, so the design called for an Atmel ATmega128 to function as the CPU, which is only usable with an STK500 and attached STK501 top module, since prototype PCBs and small surface mount soldering are beyond the resources of the class.
