Distributions of magnetic and plasma parameters of small-scale flux ropes for Category I. (a) The average magnetic field magnitude; bin size is 0.1 nT. (b) The proton temperature Tp with 0.005 × 106 K as bin size. (c) The proton number density with 0.1 #/cm3 as bin size. (d) The average proton beta with 0.1 as bin size. The format is the same as Figure 3.