A number of things, actually. One of which is some really break neck speeds.
I've gotten up to 240 Mbit/s on the downlink! Looks like the bottleneck might be backhaul provisioning or just my distance from the site. Safe to say, FLOW's network is SUPER potent... note the packet loss btw; I assume some more work needs to be done on tuning Band 12 (on this specific site). I suppose this is in pursuit of VoLTE over said Band.
It's Uplink CA, the same technology that bonds the downlink is working on the uplink/upload. I do think this may be an overestimation Speedtest's part. Band 4 & 17 usually cannot be bonded (#Physics). FLOW does uplink CA on Bands 2 and 4... Do continue testing and see if you're seeing upload over 60; that's usually the sign.
https://i.imgur.com/w9VkNbb.jpg
https://i.imgur.com/br9oVg0.jpg
https://i.imgur.com/zkBut67.jpg
New Digicel LTE bands, I think band 41 is for Thier TDD LTE network. Band 12 20mhz is an anomaly, but other users picking it up at that bandwidth.