EK SuccessHeavy Duty Vertical Slot Punch, Light Grey, 2.57 x 7.98 x 21.03 cm

This is a great little tool and very easy to use. The actual slot is quite tiny on first punch but easily made bigger by punching next to it to make the slot the length you require.

Punches holes through cardboard brilliantly

This punch is great and is indeed heavy duty.... but I expected the slot it punched to be much much bigger...I'm sure I can find a use for it, but it was a tad disappointing to see how small the punched size was...

Hole size, as the corners are rounded: gross 8mm x 2mm, nett 7mm x 2mm. The nett size, of course, is what matters if you're trying to put something through the slot. The hole shape is termed 'stadium' aka 'pill' or 'pill-capsule'. If you push the Slot Punch onto your card as far as it'll go, it gives a margin of 0.9mm from the edge of your paper or card, and I use that as an extra way to position it consistently if I'm needing to punch more than once.I use the Slot Punch in papercrafting e.g. to add a reversible message to a greeting card or add ribbon to a card (see photos). Quicker, easier and more consistent than using a crafting knife to make the hole, especially as the Slot Punch produces nicely rounded corners.Although there's an integral arrow showing you where the hole will occur, it takes a bit of practice to be able to line up with pin-point accuracy. I tend to have to punch more than once, to get a slightly wider hole, as my ribbon width tends to be a minimum of 1cm, but I find the punch so handy I don't mind at all.Punches well in cardstock up to 350gsm. You need to give it some welly for 450gsm cardstock. Definitely doesn't do construction card of 2mm thick. But that still covers a good range.