Yes!

On one condition, that they're made from non-metal materials.

But you don't have to take our word for it! Here's some proof:

Pictured below is a screenshot from the Government of Canada's Website stating that knuckles made of materials that classify as plastics (such as ABS and Carbon Fiber, which is what Monkey Knuckles are made of!) are legal in Canada.

To view this on the Government of Canada's website CLICK HERE and scroll to the "Brass Knuckles" portion (Section 43) located under the "Weapons" section.

Also note that even though Monkey Knuckles are legal in Canada, "Their misuse may nonetheless be punishable under other laws."