Hi, Juan de Fuca.  Effective mouse guards can easily
be made from 1/2" hardware cloth.  Cut a piece 3" x
entrance width, fold 90 degrees lengthwise to make a 1
1/2" x l l/1" angle and secure with push pins.  I have
posted recently my argument against using entrance
reducers, controlling ventilation air flow with the
size of the upper entrance.  This required mouse
guards such as the above.  Dan

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