Hi Dave - That would be the 9 keyway Rollmaster.
Here's the reason -
Bob McNamara who originally owned Rollmaster secured the sole aftermarket rights to the IWIS chain .
IWIS are a German maker and they are used by BMW and Mercedes.
Bob only used the IWIS on the 9 keyway piece - not the 3 keyway.
He even went to the extent of building a chain tester - His company rep. got that good other chain makers would send him their product for testing (mainly Indian and Chinese companies) He reckoned most broke at HALF the testing strength of the IWIS chain.
Rollmaster has since been sold - but I intend on finding out f they still have exclusive rights.
Interesting fact - IWIS have tried to break the contract with Rollmaster many times so they can sell to other aftermarket t/c companies.
Sorry for the lecture -but its useful info.
