The one linked immediately above is well-tested by TS users at this point and has now replaced the aging DVD batteries of many tapers including myself. I run an R44 off of one using a polarity inverting cable to accommodate the R44's DC input requirements. It provides a higher output amperage capability through it's 12V port of 6A (veses 1A for the one linked in the original post). I'm not sure what the R44 draws to determine if that is necessary.
They are both made by TalentCell, so presumably they are similar "under the hood". Both are able to be used while charging, making both "UPS like" in functionality. The form factor and extra output ports are nice.