Their website offers an explanation as a firewall, however they offer other web services.
Fortinet Technologies (Canada) FTC20120525-12-01906-210300-23-CA 204.101.161.0 - 204.101.161.255
204.101.161.0/24
204.101.161.159 - - [02/Jun/2013:12:33:34 -0600] "GET / HTTP/1.1" 403 644 "-" "Browserlet"
204.101.161.159 - - [02/Jun/2013:12:33:35 -0600] "GET / HTTP/1.1" 403 644 "-" "Browserlet"
204.101.161.159 - - [02/Jun/2013:12:33:35 -0600] "GET / HTTP/1.1" 403 644 "-" "Browserlet"
204.101.161.159 - - [02/Jun/2013:12:33:35 -0600] "GET / HTTP/1.1" 403 644 "http://www.google.com" "Browserlet"
204.101.161.159 - - [02/Jun/2013:12:33:36 -0600] "GET / HTTP/1.1" 403 644 "http://www.bing.com" "Browserlet"
204.101.161.159 - - [02/Jun/2013:12:33:36 -0600] "GET / HTTP/1.1" 403 644 "-" "Mozilla/4.0 (compatible; MSIE 6.0; Windows 98)"
204.101.161.159 - - [02/Jun/2013:12:33:36 -0600] "GET / HTTP/1.1" 200 2734 "-" "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_7_2) AppleWebKit/535.7 (KHTML, like Gecko) Chrome/16.0.912.63 Safari/535.7"