Write content and product descriptions for my website

We have a number of pages across our 12 websites that have very little content, weak content or content very similar to other product pages.
We need to have detailed product descriptions (300 words minimum) written for each of these products.
This content must be unique and should be written in a professional manner.
The goal to be achieved is to improve our ranking within the search engines and provide the user with more detailed information.
We will start by having 5 pages rewritten and if we are happy with the results there is potential for further content to be written for our products, articles and websites.

the 5 pages we have chosen for this exercise are as follows:
1. https://www.lockoutsafety.com/product/lockout-safety-labeled-do-not-operate-coloured-lockout-hasp-10-holes/
2. https://www.lockoutsafety.com/product/lockout-safety-lockout-bag-plug-hoist-control-cover-small-large/
3. https://www.lockoutsafety.com/product/lockout-safety-miniature-circuit-breaker-lockout/
4. https://www.lockoutsafety.com/product/lockout-safety-miniature-circuit-breaker-lockout-with-twister-screw-y/
5. https://www.lockoutsafety.com/product/lockout-safety-plastic-lockout-hasp-3-holes-45-mm-clearance/

Please provide me with a time frame for project delivery aswell as a price.
Thanks.