There's nothing requiring that an unrolled linked list has a fixed number of elements per node. It's just easier to reason about the performance results by fixing the number. This looks like an unrolled linked list with variable elements per node, which allows it to do things like allocate a single node for an entire bulk add operation.

List starts with array which has 10 elements(default just like ArrayList) unless you say otherwise(new GlueList(capacity)).

You can say 'allocate me 10million elements' and there will be 1 node :)

It's just a constant.