Thanks for all the replies, they have been very helpful.
This seems to be the best one I could find for the price. Has anyone had any problems or experiences using these?
Link: https://www.everythingtrackandfield.com/detail.aspx_Q_ID_E_2831_A_rnd_E_13
Seems funny to be asking about blocks like that, but I dont want to spend a bunch of money on something that is going to break or not do what it should do.