These hammer weights are used and contain some cracks in the plastic from regular use but should be good for quite a bit more use and at this price you could replace them several times for the cost of a new one. I applied reasonable finger pressure trying to break them and discarded any that broke. They might be the older style or the newer style but either will work. These hammers will also fit the models shown below.
Roland A-90 EX
Roland RD-500 (type 2)