Oki 390/391 Handbook page 17

Bottom feed (continuous forms only, thickness to 0.017" [0.44mm])
• Single-part continuous forms
– 12 to 24 lb
– Minimum 3" wide
• Carbonless, multi-part forms
– Original, plus 4 copies
– 9 to 11 lb
– Minimum 3" wide
• Interleaf, multi-part forms (with carbon paper)
– Original, plus 4 copies
– 10 to 12 lb paper, with 9 lb carbon
– Minimum 3" wide
• Continuous-feed envelopes
– 24 lb maximum
– 6.5" to 9.5" wide (envelope itself)
• Labels
– minimum 3" wide
– maximum 10"(ML390 Turbo) or 16" (ML391 Turbo) wide
• Card stock: papers up to 120 lb maximum
10 Loading Paper