Product review (5 stars): Silicone lid excellent!
Fits my pyrex bowls perfectly and stays in place. I have used it in the microwave many times and still in good shape. Also used in the fridge and holds tight as advertised. Have not used in the oven yet, however have used in microwave on high settings for 10 mins. or so, and held up great.  Also, food doesn't stick to it and washes easily. Just wash with soap and rinse. Will revise review after trial in oven.  Since my purchase, I bought another smaller one and very happy with it also.