Kev cuam tshuam lub zog----- Piv nrog rau cov tsoos (α)-PPH raj, (β)-PPH raj muaj qhov tseem ceeb ntawm qhov kub thiab txias tsis kam.
Qhov kub thiab txias----- Raws li daim ntawv thov tiag tiag, qhov ntsuas kub ntawm (β)-PP-H raj yog los ntawm -20 ℃ to +110 ℃.
