I let them thaw a couple hours at room temp in the baggie then warm them up a couple minutes under a light. When they feel warm to the touch I feed them off. I have been doing this for almost a year and never any problems. I warm them on top of the BP's cage to pre scent but the boas don't need pre scent at all. I barely get the rodent dangled and they strike. Now the BPs like a little dance before dinner!