Hello and welcome to the forum. The Mixmaster is supplied with three BNC leads to connect to the oscilloscope, an engine–block ground lead, and a set of 4 short secondary ignition leads (PP339). Additional packs of secondary ignition leads can be purchased separately.
Depending on the Pico automotive oscilloscope kit you own, you may already have a number of the ignition pick up leads (PP178). These can be purchased separately and do benefit from the additional length (1.8 metre)
An alternative purchase could be the Mixmaster secondary ignition pickups (pack of 4) PP339 to add to the four that are included with the Mixmaster purchase, giving you a total of 8 SHORT pick up leads.
I hope this helps but please feedback if you need any further information.