What Size S-Biner for a CRL?

Hello all. I have promised to include two S-Biners for a CRL in my Hammock Camping Gear Giveaway but when I started to pack all of the stuff last night I realized that I hadn't used a CRL since switching to hammocks and when I used them as a dirt dweller I used knots and not gadgets. What size S-Biner is adequate for use with prussiks on a CRL? I have size 2, 3 & 4 (aluminum/metal).

Thanks

personally I would go with a #1. but since you already have a #2, go with that IMO. anything beyond a #2 is probably too big. to each his own