When it comes to Strength training equipment the one kind of company I believe best suites the those two words is Lifeline USA. They have all kinds of cables to add resistance to certain exercises and stability balls that help u achieve results faster then most ones I used, not saying the rest arnt good they're awesome. Thought I might reccomend some of these products for people or they can go to see what they have at:
Lifelineusa.com
Lifelineusa.com