The Glendalough 17yo single malt mizunara has matured for 15 years on ex-bourbon casks and has been finished for no less than 2 years on Japanese Mizunara oak. Mizunara is notorious for being incredibly porous, which means there is a lot of loss due to leakage. But this also ensures that the whiskey can penetrate deep into the pores so that the unique flavor of the mizunara wood enriches the whiskey in a short time.