Clearly Perfect Slotted Trimmer A/B
No need to rotate fabric to realign.
Other uses include: square-up hour glass blocks, strip piecing of half-square triangles, strip-tube method of block construction and fussy cutting.
Trim up to 11 sizes from 1 1/2" to 6 1/2" (Two trimmers allow for full & half-inch sizes).
https://www.youtube.com/watch?v=VbKd4TIVKtA&t=1s