zlacker

>>ivank+(OP)
This review for the linked led strip is interesting:

This is a perfectly usable (and subjectively bright) LED strip, but beware, the specified lumens are a lie. My power meter reports a draw of 33W and another reviewer reports ~38.6W. The maximum efficiency of a 5730 SMD LED is ~110 lumens/watt, so this strip is outputting at most ~3630 lumens. Seller's description of "45-50LM" per LED would lead you to believe this can output 15000 lumens or ~454 lumens/watt. This is far outside the world record 200 lumens/watt bulbs and even outside the theoretical physical limit of 250–370 lm/W.

>>windsu+mc1
I've come across the same sort of exaggeration on eBay when I was buying LED bulbs a year or two ago. An awful lot of bulbs claim to be much, much brighter than they can possibly be; it wasn't uncommon to see `3W' bulbs claimed as outputting 500-600lm, which would place them at ~170-200lm/W. I was always disappointed with their brightness when I got them, until some googling revealed that, as a rough working figure, 80lm/W was more realistic. Once I started working on that basis, the bulbs I got were more in line with my expectations.