These Marcy® Olympic dumbbell bars are made of chromed steel for many years of use. They feature knurled handles for a better grip, and they come with weighted locking collars.
Just as the other reviewer stated, the collars are useless and will not hold anything heavier than a 10 pound plate. Basically, any exercise that causes the bar to move in an other than horizontal position will result in the weight sliding off either end of the bar. Absolutely do NOT use these for any exercise performed over your head or chest. For the limited amount of weight you can safely use with these, you're better off using the less expensive standard size weight sets which have threaded collars and work much better.
The collars on these weight sets just don't work! I received a pair of these for Christmas and every time I have tried to use them the weights just fall off. The only way I've been able to keep the weights on is to tighten the collars with a wrench, so if you ever want to change the weights it is such a pain! You'd think for a dumbbell the first thing they would make right is the collars! Do not buy unless you want weights falling on your feet!