AnoperatorTonaBanachspaceXissaidtobean(m,∞)-isometry, if max 0≤k≤m k even ∥Tkx∥=max 0≤k≤m k odd ∥Tkx∥, forallx∈X. Inthispaper,westudyunilateralweightedshiftoperatorswhichare(m,∞)isometriesforsomeintegersm. Inparticular,weshowthatanypowerofan(m,∞)-isometry isnotnecessarilyan(m,∞)-isometry.Wealsostudystrict(3,∞)-isometriesonR2andgive anexampleofastrict(2n−1,∞)-isometryonC2, foranyoddintegern.