Letter Checker Canada Post Slot of Doom Thickness Gauge Tool Template 5mm 20mm


Shipping to United States: $4.66

Let me introduce the Letter Checker! Take away the guessing when it comes to mailing your product.
This is the perfect tool to help you make sure your package isn't too thick to be sent Lettermail.
These gauges are 3D Printed with PLA plastic which is not harmful to you or the earth. PLA is made from renewable sources!

Our Letter Checkers are not small like most of our competition, the large slot is 10 11/16" wide and the small slow is 8 15/16" wide. The slot height is exactly 20mm for the large slot and exactly 5mm for the small slot.

Our Letter Checkers are sent lettermail without tracking. Please allow 5-10 business days for Canadian and US deliveries. International orders may take 10-14 Business days.

Reviews (3)


Finally. Something that saves me from going to the post office to check whether my envelope fits through the dreaded slot of doom. It save money and super convenient. Seems like it will last. Heads up: The post office informed me that the letter has to slide easily through the slot. You can't have to stuff it through. Bummer.

Thank you!!!! Fast Shipping!!!!

I had a makeshift version of this I’d made from cardboard, but wanted something more sturdy. Nice to get it in a fun colour too (purple)! If you’re a Canadian seller and can send any of your goods via lettermail, one of these “slot of doom” checkers is invaluable!!

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