Marshalltown permashape stainless steel

[rtb]

Hi all,
Complete beginner at plastering... been given Marshalltown permashape stainless steel trowel which has filing down the middle of the underside of the blade which i guess is where the rivets have been filed down rather than smooth and polished. Is this normal?

Any answers appreciated!
RTB.

 

[S a plastering]

Yep

 

[rtb]

Ok Thanks.