The trusty comb bind holds your A4 pages together with 21 rings.
The Summary Notes books are roughly 40 sheets plus a back and front cover and come with a 12mm comb bind.
If you wish to add extra pages, we recommend going up to at least a 14mm comb bind.
10mm - holds up to 45 sheets of 100gsm A4 paper
11mm - holds up to 55 sheets of 100gsm A4 paper
12mm - holds up to 65 sheets of 100gsm A4 paper
14mm - holds up to 85 sheets of 100gsm A4 paper