From the publishers webpage:
Specialist troops offer advantages the wise commander can exploit, or prevent the enemy from making use of their own advantages. Anti-armour and anti-aerospace specialists level the playing field for other troops, whilst recon experts provide vital information and commandos take advantage of it.
Specialist Forces presents information on these experts, along with rules governing their functions and equipment for their use. Mercenaries hope they will never be confronted with chemical or nuclear warfare, but if they are this volume has the necessary information. It also covers the operations of specialist formations ranging from armoured infantry to security formations and intelligence commandos.
The unique world of Starmercs is also explored, with information on the operations and equipment undertaken by forces whose primary asset is a starship. Modules for converting a conventional ship to a mercenary transport are presented, along with specialist mercenary tickets.
Inside you will find:
Special Operations and Special Forces
Combat Specialists
Reconnaissance and Stealth Specialists
Engineering and Heavy Weapons Specialists
Protected Forces
Non-combat Specialists
Security and Intelligence Specialists
Starmercs
Boarding Actions
Mercenary Vessels and Modules
Requires the use of the Mercenary box set