What is the spline size of the 39-138 & 39-139?

A quick learner from los angeles says:
What is the spline size of the item 39-139 casement operator? I am looking for this type and find 5/16 splines but can't find a matching set of an operator and folding handle. The folding handle #39-205 at 11/32 doesn't work with 5/16 operator, as it strips out.

Thanks
Steve
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Mike from SWISCO responded:
The 39-205 handle fits the 39-138 and 39-139 style operator. To make sure, I pulled a handle and operator from stock and tried it out. The handle fit perfectly.
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