This is a ‘second fix’ nail gun, meaning it's suitable for ‘finishing off’ work where nails may be visible. You can read more about different types of nail guns in this useful Screwfix guide.
This Nail Gun uses only 16-gauge, 20-degree nails between the length of 32 and 64mm. Do not use any nails with this that don’t match those specifications. About 400 50mm-length nails are included with your borrow.