I was very surprised how easy this was to put on my mattress. I have a very deep queen mattress and it still fit like a glove. I do wish that it was able to be put on directly under my sheets, instead of under the mattress pad, because I feel it would prevent my allergies more easily that way. I didn't see much allergy improvement and neither did my husband. We love that it is waterproof and protects the mattress though, since we have our son in bed with us quite often.