2 sheave wheel pulley balance block

This is a simple two-sheave pulley balance block I made for 10mm or 3/8" rope to use on my boat.
I designed this to go inside my sailboat's boom to facilitate a single-line operated jiffy reefing system. Shown here: http://www.offshore-sailor.com/media/1137/balance-block-reef-wr2.jpg?width=260&height=215

You will also need:
2 - 608 bearings
2 - 3/8" button head bolts (I had some that were 2" long and cut them to size)
2 - 3/8" low profile nuts (set with locktite)
2 - 6-32 x 1" bolts