This carburetor has the 14.95 mm dia,. barrel slide valve made for 66cc to 70cc engines, hence the name Speed. It is the same one we supply in our Gt5A-ES installation kits. Normally; Speed Carbs have a Red rectangular AC cover but also can have a Black rectangular AC cover depending on what factory makes it.
All Gru-Bee supplied carbs have an O ring inside the connection port to seal off the intake tube. Competitors brand do not have these o rings.
FYI: Smaller 48cc engines must use 14.5 mm dia. barrel slide valve carbs. to avoid being over fueled and run poorly on acceleration.. Normally 48cc carbs are identified by a Black round air cleaner cap with 4 holes and marketed as NT.