For example , the ? rst material may com prise iron , and the second material may comprise a titanium
manufacture , the ? rst Weight 160 can be a ? rst material and the second Weight 170 canbe a second material different from the ? rst material .
The ? rst material may com prise iron , and the second material may comprise a titanium
manufacture , the ? rst Weight 160 can be a ? rst material and the second Weight 170 canbe a second material different from the ? rst material .