Cole-Parmer Syringe Pump, Infusion Only, Touchscreen Control Model 74905-50 is an infuse only syringe pump. It accommodates up to two syringes. Flow rates are defined by the user and operation is based on a selectable target volume or time values to control the total infusion volume. Model 74905-52 is an infuse/withdraw syringe pump. The pump accommodates the two syringes. The unit will operate in the following modes: infuse only, withdraw only, infuse then withdraw, withdraw then infuse, and continuous. One program can be stored. Model 74905-54 is a programmable version of the 74903-42 pump. It is programmed to accept up to 800 user-defined steps — up to 40 programs with 20 steps each can be stored in memory. Model 74905-56 is a push/pull syringe pump. The pump accommodates up to two syringes for infusion and two syringes for withdrawal. This pump is designed to support infusion and withdrawal simultaneously at the user defined flow rates. The unit operates in the following modes: infuse only, withdraw only, infuse then withdraw, withdraw then infuse, and continuous. Model 74905-58 is a programmable version of the 74903-46 pump. It is programmed to accept up to 800 user-defined steps — up to 40 grams with 20 steps each can be stored into memory.