Those new dumbbell systems

[abc]

http://www.powerblock.com/frame.html

http://www.bowflexselecttech.com/catalo...d=2534374302031171&bmUID=1129765596136

http://www.megafitness.com/sta0097.html

http://www.usfitness.com/irqulodusy.html

http://www.fitnessfactoryoutlet.com/cat...ml/Products/IronMasterDumbells/50.html


there are many more... they do help save space and 'quick change'... now are they flimsy though or do they really lock well.