I have several that have a 3# combination. Mine fit under the seat in the car well and are attached via already in place bolts to the car itself. Also have one under the bed.https://www.amazon.com/dp/B00W85Q9F...Q3QRDCT12JDS07E40&ie=UTF8&qid=1500859851&sr=2
Not sure if this is what you are wanting, but they can be had in smaller sizes. They can also be used as in a car, or for airline travel.