Cluster below a numeric threshold

Hi,

I am having a dificulty here to use the cluster function.

Please, I need to cluster the data where values below the number 2 (or any other arbitrary number) for the linkage belongs to the same cluster.

Thank you in advance

%Create the pdist, link and HCA
distance_centroid_matrix=pdist(centroid_peaks);
link=linkage(distance_centroid_matrix); % In the linkage I need to the values below '2' or '2.2361'  belongs to the same cluster/peak
[hout,T,perm]=dendrogram(link ,0);

% cluster the data 
% ? ? ? ? That is the part I don't undertand. What is cutoff and depth and how should I do 
hca_cutoof=2 % ?
D=2 % ?
T = cluster(link,'cutoff',hca_cutoof,'Depth',D);