Closed Comb VS Open Comb Safety Razor

In this video I talk about the differences between Closed Comb and Open Comb Safety Razors.
This video Features a Parker 68s Open Comb Safety Razor a Parker 56r Closed Comb Safety Razor and a Vintage 1920's Gillette Old Type Open Comb Safety Razor.

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Not exactly the same threads. The new thread handles are metric and can fit the old heads, while the old ones are imperial and do not fit the new heads.