Stainless Steel Vegetable Picking, Iron Nail Protection, Finger Protector, Finger Cover, Finger Cover, Garlic Peeling and Pea Pinching Thumb Knife

Not useful at all, keeps falling off your finger. I advise against buying this

An interesting device, not a mandatory purchase. But when you have it, it is very convenient. So far I have tried it when extracting seeds from citrus fruits.