To do a direct quote from the Enya 61 CXLR specifications (this is the original ringed version)...
"Cylinder liner...Brass, nickel-plated of silicon carbide composite"
Nikasil is a trademarked name so can't be used as a description.
The later red headed 61 CXL is ABC but I was not happy with it because of a total lack of compression when hot even after I fitted the replacement piston/liner Enya sent me as an exchange.