# Significance of initialisation of Kernel in sklearn.gaussian_process.kernels

I have been going through Gaussian Processes. In one of the code I stumbled upon there is this statement, I am not quite sure of the parameters that are passed to initialise it. Please help me.

from sklearn.gaussian_process.kernels import RBF, ConstantKernel as C

kernel = C(1.0, (1e-3, 1e3)) * RBF(10, (1e-2, 1e2))


I know what Constant kernel and Radial basis function are. But I am not sure why these parameters are being passed and what it means. Also why are they being multiplied??

I have gone through the sklearn documentation page but could not find anything useful.