The pulleys are GT2 20T, mounted with M5 bolts, so you want to get the 5mm Bore pulleys.

You need 7 toothed and 1 idler. When i ordered them i was lucky to find a 8pc and single for purchase. looks like now its 5 and 10 so you will have some extras.

Toothed: https://www.amazon.com/Onyehn-Timing-Bearing-Suitable-Printer/dp/B07J4JC2N7/ref=sr_1_13?dchild=1&keywords=gt2+5mm+bore+pulley&qid=1601504841&sr=8-13

Toothless: https://www.amazon.com/BIQU-Aluminum-Toothless-Timing-Printer/dp/B01H3F8LUU/ref=sr_1_13?dchild=1&keywords=gt2+5mm+20tl&qid=1601504937&sr=8-13